iLounge says they've gotten an inside look at the iPhone SDK and came up with a few interesting details, one of which is the limitation imposed on developers that they won't be able to use the dock connector to interface with accessories. That means no third-party GPS connector (or other similar devices). What supposedly will be accessible is the camera, the Wi-Fi, and the "phone" itself, which is slightly more permissive than we thought Apple would be.
As for iTunes, it seems like the iTunes Store is going to be a "hub" for application downloads. If you're a developer and want to charge for your app, you've got a method to do that through the store. This, assuming that Apple has approved your app, because they're going to "act as a gatekeeper for all applications," meaning that if you're making something a little risque or hack-ish, you run the risk of being turned down. [iLounge]