I've heard from several sources that Microsoft will issue "multiple" Longhorn beta releases, which, in my mind, casts more doubt on a late 2005 release date than any of the other claptrap I've read online. Multiple Longhorn beta releases would be a departure from earlier Windows versions, which tended to have several alpha milestone releases, two or three beta releases, and a small number of release candidate (RC) builds. John Montgomery, director of Microsoft's Developer Division, told me that although Longhorn beta 1, due in summer 2004, will concentrate on developers, the beta will be huge, with tens of thousands of managed testers and millions of external testers. Beta 2 (ETA unknown, but I'm expecting it in the first half of 2005) will concentrate on consumers and provide better fit and finish and a near-final user experience (which I take to mean that this beta release will finally include the Aero UI). As for the people who are testing build 4051, Microsoft is considering a postalpha Longhorn software development kit (SDK) drop, based on feedback, which would necessitate a new alpha build release before beta 1. I'd like to see that happen; summer 2004 is far away.