Right now, a lot of middleware devs are nervous and angry - they can't get straight answers from Apple going on a few weeks now. Steve's letter really, really made a lot of people even more angry.
Plenty of game/app makers have stopped development right now while they wait. The indie devs have been hit the hardest. hopefully it will work out for the best, but ultimately, the iPhone OS is not the platform developers thought it was. Apple has made it clear that they may sweep the rug out from underneath you at any time.
I'm not even talking about adapting to new technologies, I mean overnight sweeping changes or vague rejections on the app store. The past few weeks have made people look at other platforms for a more predictable business model. Smaller developers, whom Apple claims to be supporting with iAd, now have to look at the amount of time and money they invest in developing an app. Games can take months. To have Apple effectively kill your project through TOS changes or a random rejection is a bitter pill to swallow.
OK, I take issue with your statement right there (emboldened). Sorry if you were given misinformation but Apple made it pretty clear in the SDK EULA from the beginning that "third party" interpreters and the like were officially off-limits and grounds for rejection in the app store. Be prepared to be burned if you play with fire.