  We present results for the top quark pair cross section at the Tevatron and
the LHC. We use the resummed double differential cross section, employing the
fully kinematics-dependent soft anomalous dimension matrices, to calculate the
soft-gluon contributions at next-to-next-to-leading order (NNLO). We improve
and update our previous estimates by refining our methods, including further
subleading terms, and employing the most recent parton distribution function
sets. The NNLO soft corrections significantly enhance the NLO cross section
while considerably reducing the scale dependence. We provide a detailed
discussion of all theoretical uncertainties in our calculation, including
kinematics, scale, and parton distributions uncertainties and clarify the
differences between our work and other approaches in the literature.
