Longhorn was demoed on Monday at Microsoft"s Professional Developers Conference. One feature appears similar to a rumored feature from Apple called "piles":
A demonstration of WinFS featured a method to "stack" documents by author in a window, with the heights of the stacks corresponding to the number of documents, as well as file views that showed snapshots of documents, rather than just file names
While the Panther Piles rumors did not turn out to be true, Apple does still hold a patent on their version of this UI element.