What's the real story here: is it "Apple locks out a competitor's product" or "Apple closes a security hole in their software"? Since iPhones also sync email account information and other sensitive data it's probably not a good idea to allow any USB device to pretend to be an iPhone and suck out all that data.

Likewise, the firmware updates that tend to break iPhone jailbreaking only close security holes. Apple is remarkably apathetic about whether you jailbreak your phone, since they already made their money from the phone.