Hi, Sha from Trulia here. I worked on some of the frontend aspects of this visualization and would be happy to answer any questions. We're pulling in OSM road data and published GTFS files for public transit routing. I just linked to SF but you can also search for other cities:
http://www.trulia.com/local#commute/new-york-ny
http://www.trulia.com/local#commute/miami-fl
http://www.trulia.com/local#commute/austin-tx