Neowin.net posted a news story that Milestone 3 builds of Windows 8 are now being compiled.

There was information previously leaked that the builds we start on February 28 and that information appears to be correct. Infamous leaker Zukona has given information that the latest build of Windows 8 is 6.2.7956.0.winmain_win8m3.110228-1701 which indicates that it was compiled yesterday on 2/28/2011, via MDL. Zukona has provided a series of leaks in the past and it's among the most reliable when it comes to this kind of information.

  Windows 8 Milestone 3 builds now being compiled