Apple is switching to using a new type of tamper-resistant screw. Apple chose this fastener specifically because it was new, guaranteeing repair tools would be both rare and expensive. Shame on them. Fortunately, our always-creative hardware acquisition team has been working on this problem for a while. It's our responsibility to provide you with all the tools you need to work on electronics, and we have a solution for you!
Introducing the iPhone 4 Liberation Kit: ifixit.com/iPhone-Parts/iPhone-4-Liberation-Kit/IF182-019