Just a quick post here:
Maning Sambale already posted about the meta data added by Los Angeles Building Import. We've imported more than 1.2 million buildings and we were flattered to talk about our work at last weekend's State of the Map. You can see our slides here.
But what I find particularly interesting is how this building data stacks up against other city imports. These maps show any polygon tagged as building=value. Feedback welcome.