Are Community Promotion ads a valid place for Area 51 proposal ads? Here's why I think it would be a valid candidate ad:
SE Podcast #6 was all about the gamification of Stack Exchange.
Area 51 proposals are games as well
Games are valid candidates for Community Promotion ads
If 1 and 3 are true, then, assuming 2, then Area 51 proposals are valid candidates for Community Promotion Ads.