The good folks at iFixit have noticed that iPhone 4s taken in for service often return without their original Phillips 00 screws. Instead, they're being replaced with Apple's own proprietary Pentalobular screws. These are the same screws that are in the current-generation MacBook Air. Here's a close-up pic from an iPhone 4, courtesy of Engadget editor Nilay Patel.
Don't call them Torx screws because they most certainly are not. To get the rare, expensive tool that's meant to extract them, you'll have to be a certified Apple tech (or know one).
While you're meant to use a special driver to extract those screws, you can get them out with something else. That something else is a part of iFixit's "iPhone 4 Liberation Kit," which contains replacement Phillips screws and a driver that will remove Apple's Pentalobular screws, as well as two Phillips replacements. No, it's not the official tool but a low-cost alternative. Note that there's a good chance it will damage the proprietary screws, but you're going to throw them out anyway, right?
Opening an iPhone 4 isn't something that just anyone should do. Be careful and know your limitations. If you're ready, the liberation kit can be yours for US$9.95.
Check out the video explaining the issue and the kit after the break.