Due to feedback and reviews of the feasibility and usability of the Windows Security Rollup Packages, Microsoft has decided that we will not be releasing any further updates for Windows NT Workstation and Windows NT Server 4.xx in the foreseeable future.
Windows XP (Professional and Home) Service Pack 2 will be released in mid-2004
The Windows Server 2003 Service Pack 1 release date has been moved from late-2003 to the first quarter of 2004.
UPDATE: Wininformant has more on this issue, it might be released earlier in Q1 2004:
In an interview with ComputerWorld, Microsoft group vice president Jim Allchin said that Windows XP SP2 was still on track for early 2004. However, the company is evaluating the schedule, making me wonder if all the pressure from users is finally settling in over in Redmond. "If we don't change our mind, [that date is correct]," he said. "There are many things that can help drive that. In particular, the consent decree helped drive when we did SP1 ... We could decide to accelerate the service pack. It's not some hard-and-fast thing. We have a team. ... I don't want to get it locked down to a particular path, because something may come up. Something came up in the last couple of weeks. It's got a lot of focus here right now." What should be a big focus, sadly, is changing the service pack schedule. Again, these release need to ship every six months like clockwork.