I have an iPhone 3g (from the UK) and I live in Brooklyn, NY, so to allow me to use it I had to jailbreak it. In doing so I figured, “Why not enable multitasking?”. I’ll tell you why: I did, and its terrible, it makes the phone crawl at a snails pace. Simply loading the sms window takes a whole minute if you have a couple of applications in the ‘multitask window’. If you’re thinking of jailbreaking your iPhone 3g just to enable multitasking, don’t bother!