I've just bought a Unitek Y-2142 powered USB hub (AMD chipset) (£5 from Maplin). The hub is a 3+1 hub. There are three usb2 ports + an iPod2 charging port which happily powers my pi. Having looked at the list of powered hubs on elinux (and failling to find this brand), I am a touch worried about backpower / backfeed (hopefully different names for the same thing). I've google the problem and came accross a test you can do at stackexchange power supply - Powered hubs, backfeeding and safety - Raspberry Pi Stack Exchange and was wondering if its a good test. The test envolves unplugging everything from the pi (inc sd card) and connecting the pi to the hub using one of the pi's fullsize ports to the 'input' port of the hub. If the red led on the pi lights up when the hub is powered up then there is backpower (and an unlit red led indicates no backpower).
Thanks
Andrew