Internally, we create a GIS layer containing the Barrington Atlas grid squares for each map. This is used to guide digitization and other tasks. It occurred to us that other parties might be interested in using these grid square polygons. So we are now publishing them as KML under a Creative Commons Attribution Share-Alike license. You can get the 3 complete ones we already have (maps 22, 38 and 65) via the AWMC/Pleiades KML launch pad. We'll post more announcements here as new sets are added.