Microsoft released a preview of Windows Desktop Search 4.0 this week. The most interesting feature is that you can access the search index over the net. I've installed the preview on two machines running Windows Vista. Before v4.0 if I open a shared folder in Windows Explorer and use the search function, Vista started searching the network folder file by file and displays a note that this takes a while:

Now when you have Windows Search v4.0 on both systems Vista queries the index on the other machine and you get the results immediately.

Cool!