We've been eagerly anticipating the beta launch of Zillow for weeks now-- rumors surrounded the project. Some of that had to do with the founder, Richard Barton; his previous project was Expedia, and many people expected Zillow to be similarly ground-breaking. The beta is fairly impressive: enter an address, and Zillow returns a list of sale prices for properties in the area. They also provide analysis of sale prices on a state or county level (Use New York county for Manhattan, or Kings county for Brooklyn, etc.) In other parts of the country, this information may be a little more useful than it is in New York-- here, prices can vary widely even in a single building, so their estimates can sometimes be off by a wide margin. Still, the more information, the better-- watch your back, Property Shark! [Related: BusinessWeek has an article today about the site.]