The SEO Dominance of Zillow
priceonomics.com
priceonomics.com
Mobile is growing like crazy, but there is a saturation point where your phone is not the best device for certain kinds of activities. Tablet isn't necessarily the best device either.
I don't think that an app store strategy is going to be the next big thing for Zillow or Trulia. I think that handling mobile well is important, but I wouldn't bet the farm on mobile when it comes to real estate.
It's jut not a foregone conclusion that desktops and laptops are totally disappearing anytime in the next 5 years.