  We review recent progress in the study of transport properties of interacting
electrons subject to a disordered potential which is strong enough to localize
all single-particle states. This review may also serve as a guide to the recent
paper by the authors [Annals of Physics (2006), in press]. Here we skip most of
the technical details and make an attempt to discuss the physical grounds of
the final-temperature metal-insulator transition described in the
above-mentioned paper.
