Mike points out a few glaring deficiencies — protections? — in the iPhone SDK, namely the non-permanence of applications — only one third-party app can run at a time and it will quit when you answer a call or generally leave the app — and you can’t access the cell networks with your apps. Instead, you have to depend on Wi-Fi. This is a big suck. As far as I can tell programmers for current third-party apps have been able to access either WiFi or cell networks, which means it’s possible. However, I suspect the SDK’s controls will keep that from happening for “official” apps created by “real programmers.” Obviously this all could change at any time, but it sounds kind of nasty, especially for folks who might want to process information and input in the background. While it’s obvious Apple doesn’t want their sexy phone to crash, you can’t lock down the farm forever.