As cool as this hack is, I think you can take it a bit further.
I believe that people don't really have an idea how old a post is by looking at a date or timestamp. I think it would be much cooler to give them this kind of information:
1 minute old
5 minutes old
35 minutes old
1 hour old
5 hours old
2 days old
2 weeks old
etc....
Or maybe with the correct date between brackets, like this:
5 minutes old (07-07-2002 15:15).
Another feature of this "TIME POSTED AGO" hack could be that the admin can specify a period of when the normal date should be displayed again. For example, if a post is older than 1 month, then it will not display the '1 month old' message, but simple the date.
I've seen this feature on other boards, take a look for example at
http://www.dpreview.com/forums/forum.asp?forum=1002 (it's not a vb board though), it seems like it works very well there, and you get an immediate idea of how old posts are.
What do you think? Am I making any sence ?