  The aim of this report is to review a theoretical approach that has been
proposed recently to describe dynamic fluctuations in glassy systems (work in
collaboration with H. Castillo, C. Chamon, P. Charbonneau, J. L. Iguain, M.
Kennett, D. Reichman and M. Sellitto). Firstly, I summarize some of the main
features of the averaged and global non-equilibrium relaxation of glassy
systems, weakly sheared viscous liquids and weakly tapped granular matter, and
how these results have been successfully reproduced with a mean-field-like
analytic approach. Secondly, I explain the outcome of more refined experimental
and numerical measurements that point at examining the dynamics at a mesoscopic
scale, and the role of noise measurements in this respect. Finally, I discuss
how our theoretical approach can be confronted to new experimental and
numerical tests.
