Presenting OpenStreetMap (tiles) within google maps API (v3). This covers up the google icon and the google 'terms' link with a white strip at the bottom, while giving the required credit to OpenStreetMap. That avoids confusion and seems fair in terms of ownership of the map, however it means google gets no credit for the map display technology and seems likely to be in breach of their terms of use. Instead you might leave google credits in place, but add OSM credits