Google WMS is a WMS interface to Google Maps. This allows users to access google map data from GIS applications via a HTTP interface. It can provide Google Map image data to any GIS application that can use a WMS service for raster data.
Open source project that offer summary and download services on this page is a project that carry out their development work on other open source development sites. Their work is linked to this page via a feature called OFI, and their work is not carried out here on OSDN site.