Comment 3 for bug 96311

As if it was needed, I also confirm the behavior: none of the Ubuntu Feisty beta CDs (desktop and alternate install) are usable on a Toshiba S3.

Based on comments found elsewhere about the conflict between ata_piix and ahci, I elaborated the following work around strategy:
- install edgy (which is known to be working on the S3)
- dist-upgrade to feisty
After this installation, the system is not bootable with any of the kernels (even the one from edgy - don't know why ?!?)
- boot with the edgy alternate install CD in rescue mode
- from the rescue installer, start a shell on the root partition
- mount all necessary partitions manually (if not using a single partition setup)
- create /etc/modprobe.d/blacklist-ata_piix containing:
    blacklist ata_piix
- dpkg-reconfigure linux-image-2.6.20-15-generic
- dpkg-reconfigure linux-image-2.6.17-10-generic (from edgy)

Result: the ata_piix is now blacklisted in the initrd (thanks to dpkg-reconfigure) and the ahci is used to handle the SATA HDD.