[Velocd]

It's not too difficult, but you should consider the queries that will be called then.

If you have dynamic elements on the sides of your forum for each page, e.g. shoutbox, poll, latest threads, member of the day, featured image, sponsors.. and the data from each section is being retrieved by a query to the database.. you're looking at 6 additional queries separate of those made by the forum, at least. Things like "latest threads" require more than just one query, since the check permission function also does other queries.

Maybe this is why not too many sites have implemented this layout.

Although, this isn't to say it's not entirely impossible, to a feasible degree.

SitePoint forums makes use of showing related articles in some of its forums:
http://www.sitepoint.com/forums/forumdisplay.php?f=34 (see the right section)

So how would you go about adding dynamic tables to the left and right, of every page? Just like $header and $footer are applied to every full HTML page in vBulletin, e.g. forumhome, you could create a $left_panel and $right_panel that would be placed before the $header, then restructure the tabling in the templates (the dirty part) to accomodate these left and right panels.

This of course still requires you to go throughout each page and add those variables. If you could add them into the header template, maybe that is the better solution?

Unfortunantly I don't have the time to write any code at the moment to help you.