Slimak and Giraud report Comptes Rendus Palevol that a small proportion (<1%) of artifacts from the Mousterian of Champ Grand, in central France, come from distances over 250 km away. That long-distance transport is rare at the site, but is even more rarely observed in assessments of Mousterian assemblages.
Out of 10 artifacts with distant sources, six are from far to the north of the site (in the Loire Valley and Paris Basin) while two are from equivalent distances to the south. The site itself is in the Rhône drainage, leading the authors to conclude that the long-distance transport demonstrates interaction of peoples between at least the Loire and Rhône valleys.
Julien Riel-Salvatore notes that the conclusion of the full paper (in French) compares the Mousterian with nearby Magdalenian and Gravettian raw material origins. In the Upper Paleolithic instances, the maximum distances are not larger but the ratio of exotic materials is vastly higher, with local flints making up only a small proportion of the artifact count. He translates a snippet; I'll translate the sentence that stood out most to me:
The ratios of the primary materials seem to clearly differentiate Upper from Middle Paleolithic groups. On the other hand, though the material ratio is distinct, the territorial circuits are revealed to have a certain similarity among these occupations across time. The temporal persistence of circuits for long-distance provisioning give rise to an idea of territorial bonds connecting Paleolithic societies over time. Particularities are therefore to be found in the technical behaviors of these societies and in the details of their tool industries, and not in any differences in territorial organization. Likewise, the secondary networks spanning toward the Mediterranean document the movement of stone over geographic spaces as vast as those now recognized during the Upper Paleolithic, and underline clearly our poor knowledge of the societies of the Middle Paleolithic.
(via Julien Riel-Salvatore)
Slimak L, Giraud Y. 2007. Circulations sur plusieurs centaines de kilomètres durant le Paléolithique moyen. Contribution à la connaissance des sociétés néandertaliennes. Comptes Rendus Palevol (in press) doi:10.1016/j.crpv.2007.06.001