  The first measurements of charged particle pseudorapidity distributions
obtained from Au + Au collisions at the maximum RHIC energy sqrt(s_{NN}) = 200
GeV) using the PHOBOS detector are presented. A comparison of the
pseudorapidity distributions at energies 130 and 200 GeV for different
centrality bins is made, including an estimate of the total number of charged
particles. Away from the mid-rapidity region, a comparison between Pb + Pb at
SPS energy sqrt(s_{NN}) = 17.3 GeV and Au + Au at RHIC energy sqrt(s_{NN}) =
130 GeV indicates that the extent of the limiting fragmentation region grows by
about 1.5 units of eta - y_{beam} over this energy range. We also observe that
the extent of the limiting fragmentation region is independent of centrality at
the same energy, but that the particle production per participant in the
limiting fragmentation region grows at high eta - y_{beam} >= -1.5 for more
peripheral collisions. In combination with results from lower energies and from
bar{p} + p collisions, these data permit a systematic analysis of particle
production mechanisms in nucleus-nucleus collisions.
