Windows Longhorn Milestone 3 Build 3683 (6.0.3683 is a Lab06 (Shell) build, compiled on 6:21 PM on October 23, 2002) It is the first publicly-leaked Longhorn build, and features Plex, a WPF Desktop Settings control panel applet (although it's broken), a Sidebar (The sidebar is built into Explorer) and a new preview pane.
The build is stable enough for everyday use. Windows applications requiring Windows XP can be run with Compatibility mode. Also, some apps requiring a certain Service Pack can be installed by changing CSDVersion in the registry.
