Well here we are, a webcam that does HD at full speed.

http://www.pcmag.com/article2/0,1759,2007593,00.asp?kc=PCRSS02129TX1K0000530

http://www.pcmag.com/article2/0,1895,2007594,00.asp

From indications the quality might be fair. It indicates that USB 2.0 is needed for 1.3mp HD video.

http://download.microsoft.com/download/5/0/2/502fa35f-7bb2-4941-9338-79068a314804/TDS_LifeCamVX-6000_0606A.pdf

http://www.microsoft.com/products/info/product.aspx?view=22&pcid=1364bf8f-9f44-4599-a221-0cdd10438d60&crumb=catpage&catid=c250fb0a-1613-4550-983d-ba203f357698

http://www.microsoft.com/hardware/digitalcommunication/ProductDetails.aspx?pid=002&active_tab=overview

http://www.microsoft.com/hardware/digitalcommunication/ProductDetails.aspx?pid=002&active_tab=systemRequirements

http://www.microsoft.com/hardware/digitalcommunication/features.mspx

I expect more will follow.