The Los Angeles Times has launched an interactive map called "Mapping L.A." and features informaiton on its 87 neighborhoods. According to the times, the website was developed with Django, OpenLayers, and PostgreSQL and the data is based on the 2000 U.S. Census. But according to the Times, the map will be somewhat dynamic:
"Because L.A. is always changing, Mapping L.A. will change with it. As communities gain in size or importance, or diminish, we’ll reflect those changes in these maps. But, in contrast to the past, the boundaries we recognize today will not be lost. Every time we move a city block from one community to another, we’ll keep a record of the original map that can be republished any time it’s needed. We’ll also keep a log of changes on the site for use by anyone seeking to trace the city’s evolution. "
There is not much additional information there but the boundaries themselves, but it's a start. Perhaps they will add hyper-local news feeds?