wikipedia is a website that uses a wiki. What you are probably looking for a wiki that will integrate with vbulletin. Here is some stuff to get you started. Integrate or bridge with MediaWiki - vBulletin.org Forum CES VaultWiki
You mean a wiki, or the website Wikipedia? I'd assume the first would require a vBulletin + wiki bridge, while the latter would require some form of API or custom BB code.
The crackedeggstudios wiki is supposed to be integrated with VBulletin so that you do not need a bridge.
