Wordpress-vBulletin Threads allows you to automatically have threads posted in your vBulletin forum when you publish a new article.
WordPress-vBulletin Threads is a simple bridge between your WordPress and vBulletin installations. When you post a new article within 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.
The post content is fully customisable and uses standard vBulletin BBCode, as if you were posting from within your forum.
*Support may also be available here on WordPress.org