Windows 7 Beta is now available for download from the MSDN Subscriber area. It will then become widely available for download on Friday (9 Jan) via http://microsoft.com/windows7.
I am very tempted to go ahead and install it as the base OS on my work laptop today but as usual, Microsoft IT have created the customised image to be used internally so I will wait until next week when I have physical access to the corporate network. My home desktop is very excited as its OS is getting an upgrade this evening :)