In partial response to Iain's node:

Actually, there are several unified intermodal public transportation systems besides Philly. The New York City subway system uses MetroCards, which allow you to also ride all of the public bus lines and most of the private ones. Also, the Washington (DC) Transit Authority has an extremely integrated system. You can use the stored value tickets (and even contactless smart cards) to ride the train system, take a bus, and you can even use the cards to park your car in a parking lot so you can take the public transportation downtown. Many of the US public transportation boards are going for intermodal integration to save money and improve ridership. I know in Denver, Colorado, they reached their projected ridership for 2015 already. If it is convenient, and it's built, they will come.