You've got a couple months before OS4.0 goes live. Hope you go for it! Quick idea: quick-start ad templates that can be created and shared and sold. But not outright community sourcing, invite required. Threadless mashed with iStockPhoto. Also, thumbs up/thumbs down to allow consumer vote on the iAd
Actually, Apple hosts the ads. I guess that might limit your ability to do A/B testing, too.
It all depends on how Apple structures the ad submission process. From Steve's pause before responding to the "will ads need to be approved?" question, I am going to guess they haven't entirely fleshed it all out, yet.
