In previous measurements of the nuclear modification factor R_AA, the PHENIX collaboration has observed both a strong suppression of pi0 and charged hadron yields in central Au+Au collisions for pT > 5 GeV/c independent of pT and particle species, and an enhanced proton yield (relative to pions) at intermediate pT (2-5 GeV/c). These rather complicated dependencies on pT and particle species reflect the detailed interplay between jet quenching and other effects such as flow and recombination. Recent PHENIX measurements have extended the pT reach of the pi0 and eta meson spectra to >10 GeV/c. Additionally, detailed studies of identified charged hadrons at higher pT have been made possible by a high statistics run and newly installed Aerogel detectors. New results will be presented to discuss how and where jet quenching sets in. The suppression patterns at high pT will also be presented as a function of collision system (d+Au/Cu+Cu/Au+Au) and collision energy (62.4 and 200 GeV).