Either AfterEffects or Motion can do that job. The COW has a few tutorials on setting up a video wall template that could get you started, creating it for free. Or you could dig up someone’s template and drop the video into preset zones. Digital Juice is now selling packages like that, sets of complete AE project files you can customize. Personally, I could never afford a large set of those considering I’d only ever use one or two, but it would be cool to buy and download individual ones on the fly as the need arose. Sonicfire PRo is starting to do somethign liek that for their smart sound customizeable music; you do everything thru the web… assuming your NLE has an internet connection, of course… stuff is getting more “cloud-like” allatime, I tell ya….