  We review recent theoretical developments in understanding the many-body
perturbative QCD dynamics of strongly-interacting hard probes in dense nuclear
matter. The relation between initial- and final-state parton scattering in
nuclei and the quark-gluon plasma and experimental measurements of the Cronin
effect, nuclear shadowing, jet quenching, modified di-hadron correlations and
forward rapidity particle suppression in p+A and A+A reactions is clarified.
Our approach emphasizes the process dependence of nuclear effects and outlines
the techniques for their dynamical calculation and incorporation in simulations
that build upon collinear factorization in QCD.
