People seriously need to learn what is and is not actually the "theft" or "borrowing" of IP. I work in music and this kind of crap is commonplace there as well.
In music, there are only so many chord progressions and so many words in the English language. There have been literally millions of songs written in the history of pop music. Any time someone gets a hit song, there are a half dozen other writers who did something similar who want to make a big stink and file lawsuits claiming theft. It happens, get over it, people come up with similar ideas all the time.
If I have an artist bring me a song that sounds like one I've written, or am working on but haven't released, I'll reject theirs. Redundancy is boring. Beyond that, I decide what I work on and release. I have a right to reject material for any reason, including because it would hamper my ability to market my own writing.
This situation is no different. Anyone who believes that Apple wasn't already planning to implement WiFi Sync in iOS is an absolute fool. It's up to them when and how they do so and rejecting the app was in their interest and within their rights.
How would the developer have reacted if they accepted it, let him make money for a while, then implemented it in the OS and gave away their better version of it for free. His business would be dead and he'd be mad that they didn't warn him about it.
Every other person on this forum has publicly suggested WiFi Sync for iTunes, does that mean we all had the idea first and should sue for the theft of our IP? No, certainly not. This developer is only different in that he actually made something that worked. I applaud those efforts, but this is a far cry from any kind of theft.