  It has been established that "hard probes", observables involving
high-momentum transfer, provide useful tools for studying the hot, dense medium
created in nucleus-nucleus collisions at RHIC. The nuclear modification factor,
azimuthal correlations, direct photon production, as well as the dependence of
the nuclear modificaton factor on centrality and angle with respect to the
reaction plane are critical for understanding the early dynamics of such
heavy-ion collisions. We will review recent results from PHENIX for particle
production at high-pT and discuss their implications.
