Can the Apple 10W USB charger be used with a 7-port USB hub to charge iPad 2, iPhone 4S, and other devices at the same time when traveling?
You typically will need one high-powered (5W) USB port for each of such devices to charge efficiently. The iPad alone requires more to charge, hence the non-standard 10W adapter. In addition, the USB hub itself is not likely to provide the necessary wattage to any of the ports (these usually are low-powered ports), so chances are not even one device will efficiently charge when connected alone to such a hub.