After trying --image_size=4GB and failing I used --image_size=$(expr 1000 \* 1000 \* 1000 \* 4). This failed again in a rather amusing way, instructing me to use 4G instead.
zyga@W510:~/Pobrane$ linaro-media-create --image_file nano-daily.img --dev beagle --rootfs ext4 --hwpack hwpack_linaro-omap3_20110426-0_armel_supported.tar.gz --hwpack-force-yes --image_size=$(expr 4 \* 1000 \* 1000 \* 1000) --binary linaro-natty-nano-tar-20110426-0.tar.gz
------------------------------------------------------------
Installing (linaro-hwpack-install) hwpack_linaro-omap3_20110426-0_armel_supported.tar.gz in target rootfs.
Unpacking hardware pack ...Done
Updating apt package lists ...
Ign file: ./ InRelease
Ign file: ./ Release.gpg
Ign file: ./ Release
Ign file: ./ Translation-en
Ign http://ppa.launchpad.net natty InRelease
Get:1 http://ppa.launchpad.net natty Release.gpg [316 B]
Ign http://ports.ubuntu.com natty InRelease
Ign http://ports.ubuntu.com natty-security InRelease
Ign http://ports.ubuntu.com natty-updates InRelease
Get:2 http://ppa.launchpad.net natty Release [9753 B]
Get:3 http://ports.ubuntu.com natty Release.gpg [198 B]
Get:4 http://ports.ubuntu.com natty-security Release.gpg [198 B]
Get:5 http://ports.ubuntu.com natty-updates Release.gpg [198 B]
Get:6 http://ppa.launchpad.net natty/main armel Packages [10.4 kB]
Ign http://ppa.launchpad.net natty/main TranslationIndex
Ign http://ppa.launchpad.net natty/main Translation-en
Get:7 http://ports.ubuntu.com natty Release [39.8 kB]
Get:8 http://ports.ubuntu.com natty-security Release [23.2 kB]
Get:9 http://ports.ubuntu.com natty-updates Release [27.2 kB]
Get:10 http://ports.ubuntu.com natty/main armel Packages [1528 kB]
Get:11 http://ports.ubuntu.com natty/universe armel Packages [5867 kB]
Ign http://ports.ubuntu.com natty/main TranslationIndex
Ign http://ports.ubuntu.com natty/universe TranslationIndex
Get:12 http://ports.ubuntu.com natty-security/main armel Packages [17.1 kB]
Get:13 http://ports.ubuntu.com natty-security/universe armel Packages [7027 B]
Ign http://ports.ubuntu.com natty-security/main TranslationIndex
Ign http://ports.ubuntu.com natty-security/universe TranslationIndex
Get:14 http://ports.ubuntu.com natty-updates/main armel Packages [73.3 kB]
Get:15 http://ports.ubuntu.com natty-updates/universe armel Packages [24.1 kB]
Ign http://ports.ubuntu.com natty-updates/main TranslationIndex
Ign http://ports.ubuntu.com natty-updates/universe TranslationIndex
Ign http://ports.ubuntu.com natty/main Translation-en
Ign http://ports.ubuntu.com natty/universe Translation-en
Ign http://ports.ubuntu.com natty-security/main Translation-en
Ign http://ports.ubuntu.com natty-security/universe Translation-en
Ign http://ports.ubuntu.com natty-updates/main Translation-en
Ign http://ports.ubuntu.com natty-updates/universe Translation-en
Fetched 7628 kB in 56s (136 kB/s)
Reading package lists...
W: Duplicate sources.list entry http://ports.ubuntu.com/ubuntu-ports/ natty/main armel Packages (/var/lib/apt/lists/ports.ubuntu.com_ubuntu-ports_dists_natty_main_binary-armel_Packages)
W: Duplicate sources.list entry http://ports.ubuntu.com/ubuntu-ports/ natty/universe armel Packages (/var/lib/apt/lists/ports.ubuntu.com_ubuntu-ports_dists_natty_universe_binary-armel_Packages)
W: Duplicate sources.list entry http://ports.ubuntu.com/ubuntu-ports/ natty-security/main armel Packages (/var/lib/apt/lists/ports.ubuntu.com_ubuntu-ports_dists_natty-security_main_binary-armel_Packages)
W: Duplicate sources.list entry http://ports.ubuntu.com/ubuntu-ports/ natty-security/universe armel Packages (/var/lib/apt/lists/ports.ubuntu.com_ubuntu-ports_dists_natty-security_universe_binary-armel_Packages)
W: Duplicate sources.list entry http://ports.ubuntu.com/ubuntu-ports/ natty-updates/main armel Packages (/var/lib/apt/lists/ports.ubuntu.com_ubuntu-ports_dists_natty-updates_main_binary-armel_Packages)
W: Duplicate sources.list entry http://ports.ubuntu.com/ubuntu-ports/ natty-updates/universe armel Packages (/var/lib/apt/lists/ports.ubuntu.com_ubuntu-ports_dists_natty-updates_universe_binary-armel_Packages)
W: You may want to run apt-get update to correct these problems
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following NEW packages will be installed:
devio flash-kernel linux-firmware linux-image-2.6.38-1002-linaro-omap linux-image-linaro-omap
u-boot-linaro-omap3-beagle u-boot-tools uboot-mkimage wireless-crda x-loader-omap3-beagle
0 upgraded, 10 newly installed, 0 to remove and 6 not upgraded.
Need to get 0 B/35.7 MB of archives.
After this operation, 0 B of additional disk space will be used.
WARNING: The following packages cannot be authenticated!
wireless-crda linux-image-2.6.38-1002-linaro-omap devio flash-kernel linux-firmware linux-image-linaro-omap
u-boot-linaro-omap3-beagle u-boot-tools uboot-mkimage x-loader-omap3-beagle
debconf: delaying package configuration, since apt-utils is not installed
Can not write log, openpty() failed (/dev/pts not mounted?)
Selecting previously deselected package wireless-crda.
(Reading database ... 9665 files and directories currently installed.)
Unpacking wireless-crda (from .../wireless-crda_1.13_armel.deb) ...
Selecting previously deselected package linux-image-2.6.38-1002-linaro-omap.
Unpacking linux-image-2.6.38-1002-linaro-omap (from .../linux-image-2.6.38-1002-linaro-omap_2.6.38-1002.3_armel.deb) ...
Done.
Selecting previously deselected package devio.
Unpacking devio (from .../devio_1.2-1build1_armel.deb) ...
Selecting previously deselected package flash-kernel.
Unpacking flash-kernel (from .../flash-kernel_2.28ubuntu19_armel.deb) ...
Selecting previously deselected package linux-firmware.
Unpacking linux-firmware (from .../linux-firmware_1.52_all.deb) ...
Selecting previously deselected package linux-image-linaro-omap.
Unpacking linux-image-linaro-omap (from .../linux-image-linaro-omap_2.6.38.1002.3_armel.deb) ...
Selecting previously deselected package u-boot-linaro-omap3-beagle.
Unpacking u-boot-linaro-omap3-beagle (from .../u-boot-linaro-omap3-beagle_2011.04.2-0ubuntu1_armel.deb) ...
Selecting previously deselected package u-boot-tools.
Unpacking u-boot-tools (from .../u-boot-tools_2010.12-2_armel.deb) ...
Selecting previously deselected package uboot-mkimage.
Unpacking uboot-mkimage (from .../uboot-mkimage_2010.12-2_all.deb) ...
Selecting previously deselected package x-loader-omap3-beagle.
Unpacking x-loader-omap3-beagle (from .../x-loader-omap3-beagle_1.5.0+git20110325+b6bbfe7-1ubuntu1_armel.deb) ...
Can not write log, openpty() failed (/dev/pts not mounted?)
Setting up wireless-crda (1.13) ...
Setting up linux-image-2.6.38-1002-linaro-omap (2.6.38-1002.3) ...
Running depmod.
update-initramfs: Generating /boot/initrd.img-2.6.38-1002-linaro-omap
/bin/df: Warning: cannot read table of mounted file systems: No such file or directory
Examining /etc/kernel/postinst.d.
run-parts: executing /etc/kernel/postinst.d/initramfs-tools 2.6.38-1002-linaro-omap /boot/vmlinuz-2.6.38-1002-linaro-omap
Setting up devio (1.2-1build1) ...
Setting up flash-kernel (2.28ubuntu19) ...
Setting up linux-firmware (1.52) ...
Setting up linux-image-linaro-omap (2.6.38.1002.3) ...
Setting up u-boot-linaro-omap3-beagle (2011.04.2-0ubuntu1) ...
Setting up u-boot-tools (2010.12-2) ...
Setting up uboot-mkimage (2010.12-2) ...
Setting up x-loader-omap3-beagle (1.5.0+git20110325+b6bbfe7-1ubuntu1) ...
Done
Cleaning up ...W: Duplicate sources.list entry http://ports.ubuntu.com/ubuntu-ports/ natty/main armel Packages (/var/lib/apt/lists/ports.ubuntu.com_ubuntu-ports_dists_natty_main_binary-armel_Packages)
W: Duplicate sources.list entry http://ports.ubuntu.com/ubuntu-ports/ natty/universe armel Packages (/var/lib/apt/lists/ports.ubuntu.com_ubuntu-ports_dists_natty_universe_binary-armel_Packages)
W: Duplicate sources.list entry http://ports.ubuntu.com/ubuntu-ports/ natty-security/main armel Packages (/var/lib/apt/lists/ports.ubuntu.com_ubuntu-ports_dists_natty-security_main_binary-armel_Packages)
W: Duplicate sources.list entry http://ports.ubuntu.com/ubuntu-ports/ natty-security/universe armel Packages (/var/lib/apt/lists/ports.ubuntu.com_ubuntu-ports_dists_natty-security_universe_binary-armel_Packages)
W: Duplicate sources.list entry http://ports.ubuntu.com/ubuntu-ports/ natty-updates/main armel Packages (/var/lib/apt/lists/ports.ubuntu.com_ubuntu-ports_dists_natty-updates_main_binary-armel_Packages)
W: Duplicate sources.list entry http://ports.ubuntu.com/ubuntu-ports/ natty-updates/universe armel Packages (/var/lib/apt/lists/ports.ubuntu.com_ubuntu-ports_dists_natty-updates_universe_binary-armel_Packages)
W: You may want to run apt-get update to correct these problems
Done
------------------------------------------------------------
proc umounted
Traceback (most recent call last):
File "/usr/bin/linaro-media-create", line 146, in <module>
args.should_format_rootfs, args.should_align_boot_part)
File "/usr/lib/pymodules/python2.7/linaro_image_tools/media_create/partitions.py", line 111, in setup_partitions
image_size_in_bytes = convert_size_to_bytes(image_size)
File "/usr/lib/pymodules/python2.7/linaro_image_tools/media_create/partitions.py", line 342, in convert_size_to_bytes
"or G[bytes]" % size)
ValueError: Unknown size format: 4000000000. Use K[bytes], M[bytes] or G[bytes]
NB: you might want to use $((4 * 1024)) rather than $(expr 4 \* 1024); also consider using multiples of 1024 rather than 1000 for SD/MMC sizes and QEMU image sizes.