[dreamhost]

haven't tried this particular hack, but his concept will work. I use postnuke .714 with encompass, and vbulletin 2.2.6 on my website http://www.annointed.net
The idea of having one database is the way to go. We personally use a custom "bridge" to integrate users etc. Basically on our site you register using vb process, which in turn sets user in pn db, and sets the session. At this point we have merged all user db, with the exception of our custom pm and buddy system. That is next. But basically one login, after registration process, through postnuke, and your in both. The only glitch I have that I see, is you don't show logged into vb untill you refresh the forum one time, then your set perfectly. Still working that display bug out.
Our key was writing a bridge, so that neither pn, nor vb db is effected, making upgrades no problem.
I applaud the author of this module, it is not easy, took us weeks, to get our program to work smoothly.