  HETE-2 has provided new evidence that gamma-ray bursts may evolve with
redshift. We investigate the consequences of this possibility for the unified
jet model of XRFs and GRBs. We find that burst evolution with redshift can be
naturally explained within the unified jet model, and the resulting model
provides excellent agreement with existing HETE-2 and BeppoSAX data sets. In
addition, this evolution model produces reasonable fits to the BATSE peak
photon number flux distribution -- something that cannot be easily done without
redshift evolution.
