Over on one of the more creatively named Microsoft blogs: "So, a booth babe and a geek walk in to a bar..." there is information and a link to a LiveMeeting about certification paths and plans for MCSAs and MCSEs when Longhorn server comes out.
That's good MCSAs and MCSEs for 2003 will remain active. Guess I should start thinking about certification for Windows 2008 MCTS and MCITP.