If you're like me, you're rebuilding machines your machines with the latest drops so you have something to play with on 'vacation' 
I wanted to make sure you knew about the drops that just hit MSDN this morning for December CTP versions of WinFX, Windows SDK, VS Extensions, etc. Links for all are below.
Now if you'd been playing with WPF and had asked Santa to get you a designer integrated with VS, you must have been nice this year. VS Extensions for December now include adesigner, codnamed “Cider“.
WinFX Runtime Components:
http://www.microsoft.com/downloads/details.aspx?FamilyId=BD3BA2D5-6ADB-4FB2-A3AA-E16A9EA5603F&displaylang=en
Windows SDK:
http://www.microsoft.com/downloads/details.aspx?FamilyId=2297BDC9-B5AE-4B8A-B601-EEF54A52867A&displaylang=en
VS Extensions w/Cider for WinFX RC:
http://www.microsoft.com/downloads/details.aspx?FamilyId=D1336F3E-E677-426B-925C-C84A54654414&displaylang=en
WinFX RC Dec CTP “Readme”:
http://msdn.microsoft.com/windowsvista/support/relnotes/winfxdecctp/default.aspx
This release is compatible with the Vista December CTP (5270) , so if you're installing that, no compatibility worries there.
Best of luck and enjoy.