Update: Just find this page from Zillow (http://www.zillow.com/howto/api/neighborhood-boundaries.htm http://www.zillow.com/howto/api/neighborhood-boundaries.htm

Update: Just find this page from Zillow (http://www.zillow.com/howto/api/neighborhood-boundaries.htm http://www.zillow.com/howto/api/neighborhood-boundaries.htm). It's in the shape file format.