In addition to the Xbox 360 accessories, Microsoft also announced the Xbox 360 Wireless Controller for Windows. Basically just a re-branded Xbox 360 controller, this works with both Xbox 360s and PCs. You may have to buy a Wireless Gaming Receiver device to make this work for your PC, but it does come with a USB cable so you can charge the controller from your USB port. The same effect could be achieved by just buying a regular Xbox 360 controller and the Wireless Gaming Receiver, so this is more an exercise in branding than a brand new product.
Pricing will be revealed before the December 2006 launch.
Product Page [Microsoft]
Press Release [PR Newswire]