I talked about Google for the desktop back in May, and now it's arrived. Google Desktop is a desktop search application the seamlessly integrates into your everyday Google searches. It is part seach engine, part indexer, and part web proxy (that's how they interject your local search results into your web search results). This is just like WinFS.
Except that it is shipping today.
And it just works.
And it doesn't require an upgrade to your operating system.
And it doesn't require you to manually tag all your files with meta-data.
And it works outside your "Documents and Settings" folder.
And it's only a 400K download.
But besides that, it's just like WinFS.