Home buyers, real estate agents and nosy neighbors now can get the power of Zillow.com in the palm of their hands. The Seattle online real estate upstart today is unveiling a free iPhone application that allows users to browse property information on more than 88 million homes in the U.S.

Utilizing the iPhone's GPS functionality, the new Zillow app pinpoints a user's location and shows nearby homes on interactive aerial maps. Much like the company's Web site, the new app also shows estimated home values, historical property records, for-sale listings and photos.

Zillow has been working on the application for the past four months, with Chief Operating Officer Spencer Rascoff saying that "it took a little while to get it right." Other real estate companies already offer iPhone applications, including Zillow's San Francisco rival Trulia.

But Rascoff said that Zillow's application goes much further than the competition, leveraging the phone's GPS functionality as well as its touch interface to allow users to move around the map with the swipe of a finger..

Zillow's app also offers data on 95 percent of the homes in the country -- which means iPhone touting users can look up the value of a home or peruse interior photos of their neighbors' pad as they walk, drive or boat around the neighborhood.

"Honestly, it has changed the way I walk around the neighborhood," said Rascoff. "It is totally different. You are learning about every home in your neighborhood. It is fascinating and it is fun and entertaining. It is sport."

Perhaps those who will benefit the most from the application are real estate professionals, who will be able to call up nearby homes while hosting an open house or showing a property.

Historically, real estate agents have used Palm or Blackberry devices, with Zillow getting a plug in this new ad from Sprint. But Rascoff thinks that may change as more people discover the interactive nature of the maps and information on the iPhone.

"I think it is going to have a really big impact in the real estate professional community," he said.

The application is free and no advertisements are appearing in the early versions, said Rascoff. Over time, he said they may explore ways to monetize the mobile version. He declined to offer any specifics. 

The new iPhone application -- which includes most of the features of Zillow's Web site -- is such an important development that CEO Rich Barton said it is "basically a relaunch of the company."

Rascoff thinks the new application will help build the Zillow brand, whose traffic has been on a sharp incline in recent months. Zillow's traffic soared 71 percent to 8.8 million unique visitors last month, a pace that Rascoff said will continue in the shorter month of April. 

Since real estate remains a very local, neighborhood-focused business, Rascoff believes that the new iPhone app will only help grow the audience for Zillow.

"It is kind of convoluted when you think about it that we look for real estate in neighborhoods and then we run back to our computer and we pull up all of the information," he said. "It is the ultimate mobile experience, shopping for a home."