Get public transit directions for selected cities with Google Maps
But here's the catch, directions are still only available for a limited number of cities, including San Francisco, San Diego, Tampa, Dallas, Austin, Seattle, Pittsburgh, and Portland. If you happen to be in cities known for their public transportation systems, like say, Washington DC, Chicago, or New York, you still only get driving directions.
For the cities that are covered, the interface is pretty nice. Just select the "Get directions" tab and enter your starting point and destination. Google Maps will pull up driving directions, or you can click "Take Public Transit" to find out how to get there without your car. The original Google Transit page is still live in case you like going to a dedicated site. You can also see the list of covered cities there.