The Windows SDK release supporting Windows 7 RC is now available on the Microsoft Download Center:

 

ISO: http://www.microsoft.com/downloads/details.aspx?FamilyID=6db1f17f-5f1e-4e54-a331-c32285cdde0c

 

Web setup: http://www.microsoft.com/downloads/details.aspx?FamilyID=f75f2ca8-c1e4-4801-9281-2f5f28f12dbd