Multisite Lisc.
 

Forgive me if this already exists.

Drupal has a multisite install that allows you to run multiple domains off of the same code base and style them accordingly. So upgrading ect.... is easier.

Is such a thing possible with VB?

I plan on running 22 separate forums for different cities.

And drupal, as limited as it is on the forum front, is looking pretty good for just that reason.