  Dynamical heterogeneities have been introduced in the context of the glass
transition of molecular liquids and the lengthscale associated with them has
been argued to be at the origin of the observed quasi-universal behaviour of
glassy systems. Dense amorphous packings of granular media and foams also
exhibit slow dynamics, intermittency and heterogeneities. We review a number of
recent experimental studies of these systems, where one has direct access to
the relevant space-time dynamics, allowing for direct visualisations of the
dynamical heterogeneities. On one hand these visualisations provide a unique
opportunity to access the microscopic mechanisms responsible for the growth of
dynamical correlations. On the other hand focussing on the differences in these
heterogeneities in microscopically different systems allows to discuss the
range of the analogies between molecular thermal glasses and athermal glasses
such as granular media and foams. Finally this review is the opportunity to
discuss various approaches to actually extract quantitatively the dynamical
lengthscale from experimental data.
