iFixIt notes that, although it looks similar, it's not a standard Torx screw. Worse, there are no readily available screwdrivers that can remove it. Even iFitIt's own 54-bit driver kit doesn't have the pentalobe-head screwdriver, adding to the frustration.
Pentalobular screws first appeared in the mid-2009 MacBook Pro to prevent you from replacing the the battery and Apple is using a similar screw on the outer case of the current MacBook Air (the primary reason the iFixIt awarded the 11-inch MacBook Air a worst-in-class repairability score of 4 out of 10).
Hackers and modders have resorted to using a 5-pointed philips head driver as a stop-gap measure to remove the pesky pentalobe screws, . It's available (along with replacement philips head screws, natch) iFixIt's $9.99 iPhone 4 liberation kit. (I also recommend iFixIt's iPhone 4 5-point screwdriver ($9.95) and MacBook Air 5-point pentalobe screwdriver ($12.95) if you like to tinker).
Obviously, it's Apple perogative to do as they choose, but it's like DRM and copy-protection before that, it's not going to stop a determined individual. So, what's the point?
Instead of switching unsuspecting customer's screws, Apple should be focusing on its GSM+CDMA and 4G antennea for the iPhone 5. June is coming up fast and Android has already leapfrogged the iPhone for the #2 spot in mobile market share, behind RIM.
What's your take on Apple's attempt to restrict access to hardware that you already own?