Windows 7/6.1.6801.0.winmain win7m3.080913-2030

Windows 7 build 6801 (with a build tag of 6.1.6801.0.winmain_win7m3.080913-2030) is a pre-beta build of Windows 7, and is the build distributed to attendees of Microsoft's Professional Developers Conference 2008.

Features

 * Windows Mail has been disabled and its executable file hidden.
 * The Superbar and desktop slideshow are hidden by default, but can be unlocked by using a tool called bluebadge.

BetaArchive

 * Extremely confused, discussion on three Windows 7 builds connected with PDC 2008

Others

 * ActiveWin.com: Windows 7 Pre-Beta M3 Build 6801 (PDC2008) Preview (Wayback Machine link, with working links to pictures)