In light of the DroidDream scare, I decided I would flash a 2.3 ROM (most recently using UD 2.5).
I've been running Lookout from the start and also used the DroidDream Killer app (didn't find it on my phone, and I added the block file from within the app)
I rebooted into recovery and did a factory wipe and cleared the dalvik cache. Then I went to apply a .zip from my SD and the file was not visible (I had dropped it on the root of the card).
So I recovered the backup image (yes, I did a backup) only to get a bootloop. In the end, I had to go into Advanced Restore and recover each partition from that image and reboot after each partition restore to get out of the bootloop. After the /boot, /system and /data partitions the bootloop is fixed.
I can replicate the bootloop (and "fix") by doing the factory wipe/dalvik steps then reflashing the last backup.
Any wise suppositions as to the cause? Is it a corrupted partition on the backup image?