Only works on Windows 8 dev preview. Not Windows 7.

An updated platform preview of IE10 for the Windows Developer Preview is now available for download. This IE10 preview adds even more support for HTML5 technologies, enabling richer Web applications with significantly improved performance. IE10’s hardware acceleration of technologies like SVG, CSS3 transforms and animations delivers faster rendering than other browsers, as highlighted in this short video.

The Fourth IE10 Platform Preview

Win 7 is, indeed, being left out of the IE10 Preview, for now.

Comment from ieblog in the link above:

ieblog
29 Nov 2011 1:27 PM
# We will release an IE10 Beta and Release Candidate on Windows 7 prior to IE10’s general availability.
Web developers interested in working with the new features of IE10 are encouraged to download the Windows 8 Developer Preview at msdn.microsoft.com/.../home.