The Windows 8 beta blog reports that the latest Windows 8 build is build 8156

It has been long since we have posted about the Windows 8 Builds. According to the information provided by Canouna on MDL Forums. The latest build compiled is build 8156 with Build string as 6.2.8156.0.winmain.111116-1900. The Build was compiled recently on November 16 and belongs to the pre-beta branch. According to the information available Microsoft would be releasing the beta version of Windows 8 during CES 2012 which is scheduled in early Jan, next year.

  Windows 8 latest build, build 8156