Good work in NYC! I've been doing some bus routes in Baltimore. Check it out the area on OSM and the wiki, which needs an update. I'd love to collaborate and chat about some lessons learned from your project. I was just at SOTM US.
Phil. Great intro to some of the issues with that data. I work for Baltimore County GIS, and have spoke at length with my colleagues downtown about importing some data to OSM. They confirmed with legal that the data is in public domain, but that they're planning to update OSM on their own. I haven't seen any such project yet, and have uploaded some data here and there to test. I'll let you know if I hear anything else.