We have released beta 1 of WinFS, the new relational file system for Windows that I'm sure you'll have heard about. It's only available to MSDN Subscribers at the moment - so feel free to get your MSDN Subscription now ! :-)
There's also help documentation for WinFS available to MSDN subscribers.
A few things to note:
There will be more noise about WinFS at the PDC so I'm going to resist saying more here but the fact that this beta has shipped is great news.
For more information, try the newsgroup: microsoft.public.windows.developer.winfx.winfs. Or take a look at the WinFS blog: http://blogs.msdn.com/winfs