Some of you may have been confused about a key issue in the iPhone SDK, I know I certainly was. You may have seen the iPhone SDK intro video that Apple released last night, in which Scott Forstall demoed syncing an application to your iPhone through the 30-pin iPhone dock connector. This allows you to do live debugs on your code, while using the application on it's native hardware. Well, if Apple didn't make it clear in their video, or on their website, you must pay the $99 (standard) or $299 (enterprise) in order to transfer an application to an iPhone for testing. You use the certificate to sign your code. You can find information about the developer certificates on Apple's DevCenter (login required). You can still use the iPhone simulator, but running it on the hardware is part of the fun.