Comment 2 for bug 458334

As a workaround, I tried zeroing out the first megabyte of the stick:

perseus:[~/iso] sudo dd if=/dev/zero of=/dev/sdb bs=1M count=1
perseus:[~/iso] sudo blockdev --rereadpt /dev/sdb

After that, usb-creator shows only /dev/sdb, and lets me format it, though the UI freezes while it does so and Nautilus opens on top of the window. I dismiss Nautilus, and /dev/sdb1 appears in the list, and I can select "Make startup disk" which seems to be working.