  We study the recent PHOBOS data on the pseudorapidity density of inclusive
charged particles in centrality-binned d+Au collisions at sqrt(s_NN) = 200 GeV.
It appears that one can understand the increasing forward-backward asymmetry in
the data by assuming that the entire distribution "shifts" backwards in
rapidity according to the initial-state kinematics, while the total
multiplicity scales linearly with Npart/2. Two models are explored, both of
which achieve a reasonable description of the available data for rapidities
sufficiently far from the pro jectiles (|eta|< 3 at the top RHIC energy). One
model uses PYTHIA as the underlying distribution, to allow a straightforward
mapping of a rapidity shift back to pseudorapidity space. The other model is a
simple analytic calculation based on functions inspired by Landau's
hydrodynamical model. The apparent success of these simple pictures to describe
the bulk of particle production over |eta|< 3 suggests that collective effects
may be present even in the "small" systems created in p+p and d+Au reactions,
active over the full rapidity range. The relationship between this and other
theoretical approaches are discussed.
