Here are the numbers CMS has used for the tt cross section from 27 May 2011:
CERN-PH-EP/2011-055 CMS-TOP-11-002 http://arxiv.org/abs/1105.5661

NLO
MCFM 157.5 +18 -19.5 (scale) +-14.7 (PDF+alphas) pb.
m_top = 172.5 GeV

Approx NNLO
163 +11 -10pb, ref Phys.Rev. D82, 114030 (2010)
m_top = 173 GeV