I've added a small convert vBulletin post to MediaWiki link in the template. This appears as a very small "->" link on the bottom left of the post, near the Report Post icon.
It is a simple tool you can use to convert vbulletin markup to wiki markup. Mostly helpful for converting a post with lots of links.
A link to a Mac Guides article could be converted to the appropriate syntax. Eg rather than changing a Mac Guides link to
[http://guides.macrumors.com/Article Article]
It could be changed to
[[Article]]
Could text wrapped in CODE tags have a space inserted at the start of each line so as to look more like the Wiki code boxes?
In forum posts, headings will usually be created by using larger text sizes and/or bold text. In Wiki code, they are created using some = characters on each side of the heading. Would it be possible to convert between the two? It could be difficult to implement since there's no standard as to what text size is what heading, so perhaps just treat any text larger than the standard size as a normal header (==), then let us edit from there.