It's not going to make your iPhone 4/4S faster, nor increase the screen size, and certainly won't add LTE network compatibility, but this $29.95 conversion kit does a capable job of disguising your soon-to-be obsolete iPhone into a believable facsimile of the upcoming iPhone 5...

This iPhone 5 conversion mod kit converts your iPhone 4 /4S to look just like the iPhone 5! (assuming that the iPhone 5 leaks are real...) ! When we first saw the leaked iPhone 5 photo from various tech sites, we were all anxious to try out! We thought that the easiest and fastest way out is to convert our iPhone 4 / 4S to look just like iPhone 5.

Via 9to5Mac