A preview version of Longhorn — the next Windows release — has been leaked. The biggest change is the use of the new file system, WinFS. It has a database architecture where each file has a key which doesn’t change regardless of where the file is on the file system. In fact, the Explorer interface itself — the folder structure — is really just a UI to a database of files. A file could appear in two places on the file system at once, for example, so it exists under two different classification systems. Think Yahoo! for your files.
“Another new feature would let the searcher “stack” files in virtual folders. Digital images, for example, could be stacked by the date a picture was taken, name or type of camera, among other criteria. Similarly, music can be stacked by nine criteria, including track number, duration or genre. Contacts can be stacked by seven criteria, including name, e-mail and address.”