Same here. Can't get Clockworkmod Recovery going, just the Samsung one. Just updated to 2.2, rooted, installed ROM Manager, and did the flash.
update.zip is created on the sdcard, but when I go to reinstall packages on the Samsung recovery, I get an error:
-- Install from sdcard...
Finding update package...
Opening update package...
Verifying update package...
E:failed to verify whole-file signature
E:signature verification failed
Installation aborted.
It's frustrating, because I want to go back to before I installed 2.2. I did a backup earlier today and just wish to go back to that, as the update to 2.2 nuked my phone back to factory default.