Windows 7 search can help you find and act on documents anywhere in the enterprise, not just those indexed on your local computer. Any server compatible with the OpenSearch standard such as Microsoft Office SharePoint 2007 servers can now be searched directly from Windows Explorer. All you need to do is install a "search connector" pointing to the server location before you can search it. Best of all, search results in explorer get all the normal functionality of files in explorer like drag & drop, preview, open, print, and e-mail.
Read the full article on David Chou’s blog at http://blogs.msdn.com/dachou/archive/2009/03/06/federated-search-in-windows-7.aspx