At the PDC, David Washington demonstrated Windows 7 searching my WSSDemo.com SharePoint site from the file explorer and from within Office applications.
One of the best features is the ability to get a document preview from the search results.

I cut a video of the relevant 2 minutes from the PDC session here http://silverlight.services.live.com/invoke/3523/xEncoderApp0/iframe.html or you can watch the entire session (SharePoint demo starts at 13:50) here http://channel9.msdn.com/pdc2008/PC16/

If you are running Windows 7 M3 then you can add the federated connector for my site from here http://www.wssdemo.com/Downloads/wssdemo.osdx