Posted details about the hacker here...
http://www.vbulletin.com/forum/showthread.php?t=224204
I was unable to determine the nature of the exploit other than the fact that somehow the user was able to edit data in the FORUMS table. I did a search in my Apache logs for a URL that contained part of the forum title he changed them to, but found nothing. Nothing odd in the vB admin logs either.
blakespot