The most recent beta of Windows Vista shows that the "Volume Shadow Copy" service is enabled and set to run by default. This old feature that came with Windows Server 2003 and older versions of XP essentially backs up documents before modification. While this is good in the sense that you really can't lose old copies of files in Windows Vista, it is bad in the sense that your boss can catch you slacking off and deleting malware is a lot trickier then it usually would be. The feature is explained by Microsoft here
, and can be disabled in the System Protection settings.
Source: ARS Technica