Google Maps has made things a little spicier for users who are looking up information on cities like New York, London, and San Francisco: outlines to show the footprints of buildings, and subway stops. Public transportation map mashups have been around for a while--take subway stop site Hopstop, which uses Yahoo Maps, for example--but this is the first time that Google has incorporated that data into its standard map search.
It doesn't look like this has spread to mobile platforms yet: I have Google Maps on my Helio Drift phone (oops, I called it a phone), and it does not have any building outlines or subway stops incorporated.
Additionally, as one Boston-based CNET editor pointed out, the same "M" logo for the New York City subway is used to represent Boston's T system and San Francisco's BART. London's Underground and Paris' Metro are marked by their own symbols. I guess that just confirms that New York City totally pwns every other city in the States.