Windows 8 Beta reports that the Windows 8 Milestone 2 has been already compiled
According to Canouna, one of the important source for Windows 8 builds have stated that build 79XX was a part of Milestone 2 and build 78XX was a part of Windows 8 Milestone 1. Here is what he posted on Russian site winreview.ru -Windows 8 Milestone 2 already compiled
Windows 7 Post-RTM: 6.1.77xx.0.winmain.xxxxxx-xxxx
Windows 8 Milestone 1: ?6.2.78xx.0.winmain_win8m1.xxxxxx-xxxx
Windows 8 Milestone 2: 6.2.79xx.0.winmain_win8m2.xxxxxx-xxxx