As posted in my earlier thread I today experienced a loss of data on my 12" PB. All mail data, Safari, iCal, Address Book as well as some Finder and System Preferences were either lost or severely damaged.
The culprit appears to be FileVault which seems to be corrupting data in the user's home directory. I was lucky inasmuch I was able to turn off FileVault. I copied my user/preference folder across from backup and all is well. Others weren't as lucky.
For more info please check out the discussion at the Apple support forum.