  We present updated predictions for the total production cross section of
top-quark pairs at the Tevatron and at the LHC, and, at the LHC, of heavy-quark
pairs with mass in the range 0.5-2 TeV. For t\bar{t} production at the LHC we
also present results at \sqrt{S}= 10 TeV, in view of the expected accelerator
conditions during the forthcoming 2008 run. Our results are accurate at the
level of next-to-leading order in alpha_s, and of next-to-leading threshold
logarithms (NLO+NLL). We adopt the most recent parametrizations of parton
distribution functions, and compute the corresponding uncertainties. We study
the dependence of the results on the top mass, and we assess the impact of
missing higher-order corrections by independent variations of factorisation and
renormalisation scales.
