  We review recent advances in the theory of strong-interaction effects and
final-state interactions in hadronic weak decays of heavy mesons. In the
heavy-quark limit, the amplitudes for most nonleptonic, two-body B decays can
be calculated from first principles and expressed in terms of semileptonic form
factors and light-cone distribution amplitudes. We discuss the features of this
novel QCD factorization and illustrate its phenomenological implications.
