When I setup sharing on Vista because of the lack of ISO mounting software, I found Search Folders in Windows Explorer and was surprised that the Shared By Me search folder showed no results. Here is the final dialog on setting up sharing:
If you look on the dialog, you see the Show me all the files I am sharing link, which brings up the Shared By Me search folder with no results, days later even:
I have 2 files on my Desktop that I think should be showing up in the search results, a Visio file and the Visio ISO file. I thought this was a decent way to expose users to the search folders, give them hints when they use other functionality, until it didn't work that is.