How about something like Action 52 concept. 52 in 1! Quality doesn't have to follow same design
It's a toss up between that and Warioware
Getting serious now, how about this for an idea -
There's a set dimension for each submission, each submission is independently hosted (or if people want I'll give away FTP details and we'll just chuck it up on some shared hosting)
There's a "master file" that acts as the actual game, the player loads up the game and starts playing the level, they fail, and when they hit restart a different game loads up, the same thing happens when they pass a level; the game would cycle through a set of levels (say 8) until they're all completed, and then you move onto the next set. Rapidly shifting mechanics give both diversity and help the game feel fresh; with the added benefit of the games being inherently simple, easy for the player to understand, easy for the dev to make.
Basically - iframes, obviously this can be iffy with some mobile devices, but it removes the need for a SVN or complicated co-ordination; devs make their game, upload it and share the details. Loading would be an issue - can we pre-load URLs yet? If not we could get fancy with some webdev.
tl;dr: We make a wrapper.