As a Google employee recently said, "Google Maps is evolving from a driving directions and business search tool, to a comprehensive representation of all the world's information, on a map." That's why Google Maps started to integrate different layers of information when you search for an address and it added a new "More" button to enable layers for photos and Wikipedia articles. Google Maps now includes in search results personalized maps, geolocated content from the web and mapped web pages.
There's a new option to search for real estate: click on "show search options" and select "real estate" from the drop-down. The search results don't seem to be powered by come from Google Base. Google shows structured information about houses and lets you refine the results by price, number of bedrooms and bathrooms. Even if there aren't too many advanced features, it's interesting to see that Google Maps wants to index all the information that could be displayed on a map.
Many real estate sites use Google Maps API and the first Google Maps mashup was HousingMaps, a site that displays Craigslist housing listings on a map. Last month, Trulia was one of the first sites that integrated Google Street View "to add efficiency to the real estate search experience and help home buyers discover more information about particular neighborhoods".
(The post was updated to reflect that the data is obtained from Google Base.)