I would guess snitz forum (
http://forum.snitz.com/). A free (AFAIK) asp based forum system. I guess they made some modifications, at least on the look, but the features look very similar.
And since we are checking out some other packages features, I saw today something cool on a vbulletin board. They have a "user online" text or icon by the username in the post...
I always disliked the who's online feature (I dont find it ver useful, maybe it's just me) but this seems to make more sense IMO. If I am reading a post and find that Brewskie was online (just by looking at his username) it may encourage me to send him a PM, for example (I guess that is what this feature means...or could be online as of "internet online" taken from their ICQ status for example?)