Why is Trulia powering WashingtonPost.com search . . .

. . . instead of MRIS’s Homesdatabase.com?  Here’s the Inman article and Trulia’s announcement.  I wonder if MRIS was in the running for this business or not?  Is MRIS syndicating listings to Trulia?  In other words, is Trulia’s inventory complete or not?  Something just doesn’t make sense here unless MRIS just doesn’t care about this kind of partnership, but that seems unlikely.  From my perspective, this is a good win for Trulia in trying to build the biggest brand in online search in the D.C. area and a blow to Homesdatabase.com.  What do you think?