Looks like Longhorn will officially ship in 2006 without the WinFS File System.
In addition, the new presentation subsystem code-named Avalon and the new communication subsystem code-named Indigo will also be made available to Windows XP and Windows Server 2003 so Longhorn will not be the revolutionary Operating System that Microsoft has initially promised to deliver.
Joe Gregorio explains this better in an article called Longhorn versus the light of day which he wrote back in November 2003.