I tried test10 today by uncommenting arjan's repository in the up2date sources file and running up2date. It couldn't mount the root filesystem due to a problem with the initrd. What happens is that the adaptec module loads fine from the initrd and scans the scsi bus, it prints a message that it is loading the ext3 module, but mounting / fails with an error code. So as a result pivot_root fails and it can't find init.
When I rebooted back into 2.4.22-1.2115.nptl, I discovered that /home (which is located on /dev/hda, my first IDE disk) had at least one corrupted directory, apparently in homedir.
My system has seen several upgrades so it isn't using fs-labels in fstab. Don't know if that's relevant, but my initrd's work fine under kernel 2.4. Also, after upgrading this machine to both RH9 and now FC1, I had to enter grub commands manually to boot because it apparently couldn't find grub.conf. This is probably because I recently added /dev/hda and changed /dev/sda to no longer be the boot disk. Reinstalling grub manually clears this problem up, but it would be nice to find a way to fix my system so that anaconda won't get confused next time I do an upgrade. And I'm wondering if this is related to the initrd confusion, since I had the same problems when building 2.5.70 myself and had to statically link with the adaptec driver so that I wouldn't need an initrd.
/etc/fstab:
/dev/sda6 / ext3 defaults 1 1 /dev/hda1 /boot ext3 defaults 1 2 /dev/hda4 /home ext3 defaults 1 2 /dev/sda5 swap swap pri=0 0 0 /dev/sda2 /f vfat gid=17,umask=002,noexec 0 0 /dev/hda2 /c ntfs gid=17,umask=007,noexec,ro 0 0 /dev/fd0 /mnt/floppy ext2 owner,noauto 0 0 /dev/cdrom /mnt/cdrom iso9660 kudzu,owner,noauto,ro 0 0 none /proc proc defaults 0 0 none /dev/shm tmpfs defaults 0 0 none /dev/pts devpts gid=5,mode=620 0 0 /dev/hda3 swap swap pri=0 0 0 /dev/cdrom1 /mnt/cdrom1 udf,iso9660 noauto,owner,kudzu,ro 0 0