  We perform a global fit to the CKM unitarity triangle using the latest
experimental and theoretical constraints. Our emphasis is on the hadronic weak
matrix elements that enter the analysis, which must be computed using lattice
QCD or other nonperturbative methods. Realistic lattice QCD calculations which
include the effects of the dynamical up, down, and strange quarks are now
available for all of the standard inputs to the global fit. We therefore
present lattice averages for all of the necessary hadronic weak matrix
elements. We attempt to account for correlations between lattice QCD results in
a reasonable but conservative manner: whenever there are reasons to believe
that an error is correlated between two lattice calculations, we take the
degree of correlation to be 100%. These averages are suitable for use as inputs
both in the global CKM unitarity triangle fit and other phenomenological
analyses. In order to illustrate the impact of the lattice averages, we make
Standard Model predictions for the parameters BK, |Vcb|, and |Vub|/|Vcb|. We
find a (2-3) sigma tension in the unitarity triangle, depending upon whether we
use the inclusive or exclusive determination of |Vcb|. If we interpret the
tension as a sign of new physics in either neutral kaon or B mixing, we find
that the scenario with new physics in kaon-mixing is preferred by present data.
