Trulia claims to be the first national real estate site to offer the feature that allows prospective home buyers to take a virtual walk down the street and tour the surrounding neighborhood.

While Trulia listings already provide thumbnail photos of homes as well as Google Maps, which include satellite imagery, Street View goes further by providing a more immersive experience. "It's a phenomenal utility in terms of being able to walk down the street to see what neighboring houses look like--things you couldn't see unless you actually drove down the street," said Trulia co-founder and CEO Pete Flint.

Street View hasn't been without controversy, however. The feature, which includes thousands of street-level photos in major metropolitan areas, has aroused privacy concerns since launching last year.

Last week, a Pennsylvania couple sued Google over Street View, alleging that pictures of their home appearing in the service violated their privacy because the images had been taken from their long driveway marked as "private road."

Google has said the claim is meritless, and noted that its site allows property owners to request that images be removed from Street View if they provide a good reason and can prove they own the property shown.

For his part, Flint said he isn't overly concerned about potential litigation. "If people have issues with what Google is taking pictures of, it's really Google that's managing the privacy issues around (Street View)," Flint said. "I know they've been very responsive to privacy concerns."

With Google recently releasing the API (application programming interface) for Street View, it may only be a matter of time before other real estate sites incorporate it also. Flint said he's not worried about that possibility because competitors such as Zillow.com, Redfin, and Realtor.com tend to use mapping tools from Microsoft or other suppliers rather than Google.

He added that Street View is part of a wider effort to expand Trulia's offerings, including a new community section called Trulia Voices that lets users ask questions of real estate professionals nationwide.

Founded in 2004, Trulia's traffic has nearly tripled from 752,000 monthly visitors to 2.2 million over the last year, according to comScore. That makes it the eighth-most-popular U.S. real estate site and the fastest-growing.

Flint also said the company's revenues had doubled since last year despite the real estate downturn. "What we're seeing is that the time people take over a home purchase is dramatically extended," he said. "So they're using independent sites like ours rather than going to a real estate agent to do research and the growth rate has been staggering."

To date, Trulia has received about $18 million in venture capital backing from investors including Sequoia Capital and Accel Partners.

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