Redfin has received approval for a free iPhone application that plots for-sale listings on a map -- the latest company looking to transform the way people buy and sell homes using mobile devices.

Redfin's foray follows iPhone apps from Trulia and Zillow.com, the latter of which has recorded nearly 700,000 downloads since its app was introduced in April. Other iPhone apps in the real estate category include the Homes.com Real Estate Search and Home Finder Real Estate Tool. Meanwhile, earlier this month, Seattle's John L. Scott Real Estate unveiled an enhanced mobile service for the iPhone and other smartphones.

Despite the crowded field, Redfin CEO Glenn Kelman believes his team has created a compelling offering that should resonate with both consumers and real estate professionals. Because Redfin operates as a broker, Kelman said the new app includes all of the for-sale listings moving through the multiple listing services.

"There hasn’t been a major consumer application for the iPhone that shows all the homes for sale," said Kelman, adding that Redfin also shows for-sale-by-owner and bank-owned listings. The app is available in the 10 markets where Redfin does business.

Kelman estimates that the Redfin app has about 30 percent more real estate listings than some of the other apps. He also said it has about 10 times the data, including photos, amount of time the home has been on the market and other pertinent real estate information.

The app also allows potential home buyers to record notes or photos of selected properties while on home tours, with that information synced with their Redfin profile page. It also works the other way, allowing a Redfin customer to receive driving directions on his or her phone for properties pre-selected on the Web site.

Kelman said the app represents a major advancement, noting that the company spent the equivalent of a "couple person-years in our R&D group building an all-native application." The result, he said, is the "fastest, most powerful" real estate application for the iPhone.

UPDATE: More from the Redfin blog.