I know this comment comes late, but I wanted to toss it out there. Reading threads right now, it's hard to tell how old the responses are without hunting for the faded and tiny text of the post date.
It would also be cool if you could put it at the top of the post and float it right. Under the post means we have to read the post to find out it is really old. It's just not fun and it's not very friendly.
Also, I don't understand why the username is repeated next to the date, since the UserBit is prominently to the left of each post...