Their roadmap page talks about downloading to a test iPhone straight from a Mac, but presumably, they'd either have their own app on the App Store in which you could play your games, or even output it to some sort of wrapper app that you could then release on the App Store yourself. Their press release says they will allow for games "to be sold and marketed on the App Store," and that seems to us like there's compensation involved somehow, either through their portal, or through Apple's setup.
Very interesting. Unfortunately, most of this is forthcoming -- their development environment is available for a free download right now, so you could start working on creating your masterpiece right away if you want, but you'd have to wait until sometime "in the next few weeks" to see what iPhone features they have planned. Part of the iPhone's draw as a programmer's platform is that it's relatively easy to develop for, and an environment like this promises to make it even easier and more accessible. Whenever you have a low barrier of entry to development, release, and sales, you end up with two things: a market possibly flooded with junk, but on the other end, lots and lots of creativity.