So, Apple released the SDK but it's not totally clear to me where we have to pay for. The SDK is free (which means we can develop apps and debug them on the iPhone simulator), but the developer program is $99 a year. What's the difference between those two and what possibilities do we have with either the SDK and the developer program? Besides, we're charged a nominal fee once, when updating to the 2.0 software, right ? But what can we do with and without that update ?