If you follow the thread to the end, you'll see that the guy renamed some variables, resubmitted and got accepted.

PhoneGap is open source. There is no "signature" that they can use to know that you incorporated code from it. They would have to disavow their own APIs in order to stop people from using it.

A bunch of phonegap apps have gotten in to the app store: http://phonegap.com/projects

Maybe that person just got unlucky and had a bad app tester.