Actual build of Windows 8 is: 6.2.7947.0.winmain_win8m2_escrow.110218-1608.
As you see is from 2011-02-18. I think that beta version will be release near. At 2011-02-28 MS want start programming M3 build. It's last version before beta. Dell said that at Q1 2012 they'll release Tablet with preinstalled Windows 8.