Today Microsoft announced the immediate availability of the $99 Lifecam Studio webcam that has a 1080p sensor thats double the size of your typical 720p cam.
The beefed up sensor isn't the only big feature as the camera has a better than average microphone and can shoot still pictures in HD resolution (2304x1728).
There aren't alot of services out now that support 1080p resolution but, give it time....meanwhile make your own HD video.