File sending via Bonjour fails in 10.8.1 Messages app

After upgrading to Mountain Lion 10.8.1, we are unable to share files via Messages app over Bonjour. We have both (the two people doing this) upgraded to 10.8.1, we've both tried rebooting, no change. We try to send the file, then after about 10 seconds, the File Transfers screen shows Failed for the transfer. Regardless of which direction we're trying to send the file, him to me, or vice versa.

However, I AM able to send files to another user that is not on 10.8.1 over the same Bonjour network.

There are no messages showing in the Console when this happens.

Any ideas?