WordPress-vBulletin Threads by WhatNiche Web Development acts as a bridge between a WordPress and vBulletin installations.
When a new article is posted in WordPress, you may optionally have this plugin automatically create a thread in your forums.
You may specify the forum to post the thread in, which WordPress categories to do this for and which user to make the threads belong to.
WhatNiche also have a Support Forum.
The post content is fully customisable and uses standard vBulletin BBCode, as if you were posting from within your forum.
More Info: http://www.whatniche.com/wordpress-to-vbulletin-automatic-poster-plugin