These neighborhood shapes are now available, zipped up in the Arc Shapefile format, for anyone to download. According to Zillow's lab, the company wants to share more than 7000 neighborhood boundaries with the community... these via SHP file format. This from zillow... " The Zillow data team has created a database of nearly 7,000 neighborhood boundaries in the largest cities in the U.S. And we'd like to share them with you! We're sharing these neighborhoods under a Creative Commons license to allow people to use and contribute to our growing database." The fine print... You are free to use the files in this database in applications as long as you attribute Zillow when you use it. You may also make your own changes to the database files and distribute them, as long as you provide them under the same kind of license and give Zillow attribution. You can grab the boundaries here