Let's say hypothetically you plug in your iPhone to charge on your friend's laptop. Your friend happens to be an iPhone developer and have Xcode open, and so immediately Xcode asks whether you want to use this iPhone for development. Of course you don't at the time...so you click the No button. Then, a few days later, your friend (who is very poor and can't afford an iPhone of his own) asks to beta test his fancy new iPhone application on your iPhone. How will your friend ever get Xcode to recognize this same iPhone again and use it for development?
From a terminal window:
defaults delete com.apple.Xcode XCKnownRemoteComputers
Be forewarned: this completely clears the list of devices that Xcode already knows about.
"Hmm, we're not able process your request."
Judging by how often we've seen this error message on the Apple iPhone Dev Center site the past couple of weeks, it seems that the iPhone SDK is extremely popular with developers. Either that, or developers are so confused by the new SDK learning curve, that they're hammering the dev center site seeking better documentation.
My guess is we're seeing a mix of the two. Developers who are unfamiliar with Mac OS X development have several hurdles to jump when learning iPhone development: Objective-C, Xcode, and of course Cocoa. There are of course similarities between Eclipse and Xcode, Cocoa Touch and Android, Objective-C and Java, but they're not identical.
Still, given a little time, I think most tenacious developers will agree that it's not extremely difficulty to pick up the iPhone SDK after having worked with, say, J2ME.