updated to the latest Chimera. no success
tried regenerating a new serial number. no success.
tried a variety of different things, all with no success.
started up an older (working) CCC backup of my OSX ML 10.8.4, which previously has iMessage working. Same problems on the backup.
right now, i'm stuck in a loop with having to re-enter my password during iMessage setup
if I enter a wrong password, it rejects it.
if I enter the correct password, it asks for it again, over and over and over.
not sure how long this has been broken.