An undelete system based on that of Windows Server 2003's versioning file system, should ship with the final release of Windows Vista. The technology, which is automatically switched on in Vista, is called 'volume shadow copy' and Vista users will see it appear under the 'previous versions' banner.
It maintains backups of older versions of files when you edit and save a new version, similar to .bak files that litter your system, but presents users with a usable interface to manage the previous backups. Microsoft says the feature can also be used in the case of accidental deletions.
Fortunately for the privacy advocates among us, the feature can easily be disabled via the system protection tab within the system properties control panel. ยต
See Also
Why Vista is late
Microsoft denies Vista will be late