According to sources close to Microsoft, recent release schedules that have popped up on the internet regarding Longhorn are inaccurate and outdated. Today Windows Client Codename "Longhorn" hit the milestone of M8-2. The next and final milestone before a beta is released is M9 which is currently due on 16th March 2005. Beta 1 of the much anticipated OS is due within May 2005. These new dates paint a picture of Beta 1 being released at this years WinHEC 2005 (late April) if its indeed ready.
On another note, Windows Server 2003 SP1 is due to RC1 on the 6th December 2004 with an RTM due Q1 CY2005.
News source: In-House