The National Association of Realtors has flipped the switch for the first two multiple listing services to go live on its Realtors Property Resource property database, and is planning to add about 15 MLSs a week by November.But Realtors whose MLSs haven't signed on to the project won't be able to sign in to a Web-based version of the database using their NRDS (National Realtors Database System) ID until the fourth quarter of 2011.More than 100 MLSs representing 265,000 Realtors have signed up for RPR, licensing their historic listings data to NAR subsidiary RPR LLC in exchange for member access to the 150 million-parcel database.All of those MLSs are expected to go live with RPR this year, said Mona Steen, RPR senior vice president of industry relations, in a blog post. The first two MLSs ...