I can confirm that my 2nd generation 1GB iPod Shuffle does not work with 64-bit Windows 7 RC Build 7100. Windows 7 recognizes it and iTunes also recognizes it, however, when I go to put music on it, iTunes freezes for a couple minutes then when it becomes usable again it shows nothing on my Shuffle.
But there is a solution until Apple updates the driver. Use the new "Windows XP Mode" feature that is in beta. I am using Windows XP Mode and installed iTunes in it and it seems to be able to sync with my Shuffle fine. Grab the Windows XP Mode beta here: http://www.microsoft.com/windows/vir.../download.aspx