So this one falls into the “we needed to pass this on to our readers, but we’re really not sure how useful it is” category. It is now possible to somewhat use FaceTime on a jailbroken iPhone 3GS with one big BUT: right now it doesn’t do video, only audio.
That said, the developer says he’s working on the video part (though of course how you’ll actually the other person and also have them see you will require a mirror or something). Here’s the video below of the Cydia hack the developer is calling “FaceIt 3GS”. What do you think? Even if video worked, would FaceTime on your 3GS be useful? Would you need to carry around a mirror with you?