Non-Mac users who are unable to use their computers to charge their iPads now have an option: major motherboard manufacturers have released driver updates that increase the power output of their USB ports. Engadget reports that Gigabyte, ASUS and MSI all have updates available. Though the updates may work with motherboards made by other manufacturers, that'd be definitely an at-your-own-risk kind of mod.
Many new iPad owners were surprised when they got their new purchases home and found that they couldn't charge the tablet from the USB ports of their Windows PCs and older Macs. There had been little communication from Apple about the increased power consumption of the iPad, and the slowness of the response suggested that testing of the new device with non-Apple hardware had been minimal or nonexistent. Apple later released a Support document with the helpful Note that read "Some USB 2.0 ports and accessories do not provide enough power to charge iPad."
Newer Intel-based Macs have switchable USB 2.0 ports that automagically reconfigure themselves as high-power ports when a device with high draw is attached. From the standard 500 milliamp (mA) 5V output, Apple USB ports ramp to 1100 mA when needed. Even high-power USB ports on newer Windows PCs and accessory hubs often don't deliver that much current, leading to the disappointing "Not Charging" icon.
The ASUS Ai Charger claims to boost charging speed by "up to 50%," though that's a pretty slippery metric. Gigabyte's ON/OFF Charge, on the other hand, promises "3x" USB power for "40% faster" charging. MSI's i-Charger software comes with a more understated - and precise - specification of 1.2A current delivered.
Engadget's post includes a video of a user installing the ASUS software on a variety of non-ASUS equipped computers. So it can be done, but since driver upgrades can potentially cause all kinds of trouble even if you have a compatible motherboard, it might be better to test this out on a with a cheaper high-power USB device before hooking up your expensive iPad...