  Interest in the dynamical arrest leading to a fluid --> solid transition in
thermal and athermal systems has led to questions about the nature of these
transitions. These jamming transitions may be dependent on the influence of
extended structures on the dynamics of the system. Here we show results from a
simple driven, dissipative, non-equilibrium system which exhibits dynamical
heterogeneities similar to those observed in a supercooled liquid which is a
system in thermal equilibrium. Observations of the time $\tau_R(r)$ required
for a particular particle to move a distance $r$ reveal the existence of
large-scale correlated dynamical regions with characteristic timescales chosen
from a broad distribution. The mean squared displacement of ensembles of
particles with varying characteristic $\tau_R(r)$ reveals an intriguing
spatially heterogenous mobility. This suggests that a unified framework for
jamming will have to be based on the connection between the nature of these
heterogeneities and the effective dynamics.
