The December CTP of WinFX has been released this morning along with some other related downloads. In addition to the WinFX Runtime Components and the Windows SDK (which has subsumed the WinFX SDK that used to be available separately), you can also download the—hold your breath while you read this one—Visual Studio Code Name "Orcas" CTP WinFX Development Tools...whew! The most exciting part of this last download is the inclusion of "Cider," the Windows Presentation Foundation designer for Visual Studio; how appropriate for the team to deliver Cider for the holiday season!
These bits are compatible with Windows XP SP2, Windows 2003 Server SP1, and the Windows Vista December CTP that was also released today to MSDN Univeral Subscribers and beta testers. You can find more information in the release notes. Tom Archer's post on the subject also points to a Get the Beta page that includes installation instructions and a link to the handy WinFX Runtime Components Uninstall Tool.
And if you're wondering, I will be releasing an updated version of my Adobe Illustrator to XAML Export Plug-In that's compatible with the WinFX December CTP. I'll post a new blog entry when that happens.