David79 that's a good find, the trouble is, as far as I can tell the iPad can't charge properly using it's own USB cable plugged into a computer or powered hub, it charges, but at a trickle rate rather than at full. My concern would be putting even more of a strain on the USB ports power output by connecting another device, I believe Apple should have doubled up the USB plugs on the iPad cable to start with, much like the ones supplied with some external USB powered hard drives.
I myself use a charger dock with iPad and iPod/iPhone connectors to charge my iPod and iPad at the same time. It doesn't have a computer connection for syncing to iTunes though, I do that through the supplied cable.
I use this one [ame]http://www.amazon.co.uk/Griffin-GC23126-Powerdock-Charger-iPhone/dp/B004BNSRGQ/ref=sr_1_3?s=electronics&ie=UTF8&qid=1299911278&sr=1-3[/ame]