IMHO this should be a critical bug. As the alternate cd fails after the partitioning step when run from usb (probaly because it uses on of the partitions as a temp dir) and the netinstall image takes a good 90 minutes to complete an install (not to mention it is very beginner-unfriendly), the install functionality should really just work off of the live cd.
I can also confirm that this is indeed a problem with the final 11-04 AMD64-image.
I posted details here at first: https:/ /bugs.launchpad .net/ubuntu/ +source/ ubiquity/ +bug/730209/ comments/ 38
IMHO this should be a critical bug. As the alternate cd fails after the partitioning step when run from usb (probaly because it uses on of the partitions as a temp dir) and the netinstall image takes a good 90 minutes to complete an install (not to mention it is very beginner- unfriendly) , the install functionality should really just work off of the live cd.