Especially with the gains in ridership they've been having in the last several years...
NYTimes - New York City Grew, but Traffic Didn’t
(c) NY Times
Apparently, in the last "boom" period that NYC's had, transit actually increased its ridership at greater rates than vehicle traffic. Which is pretty awesome; in Lower Manhattan, vehicle traffic actually decreased, as people abandoned taxis and cars for buses and the subway.
Of course, now that it's showing such rapid growth, now is when the MTA's under threat of having to reduce service drastically, if not given new life by the folks up in Albany (which they probably will be).
Who needs a better example of the communalistic relationship between quality of life and transit service than New York? Especially Manhattan; it's the place that everyone wants to live (making generalizations of course)! As crime went down, many more people wanted to ride the subway, as well as the implementation of the MetroCard, allowing for smoother transfers.
At the same time, it might be hard to find direct lessons to learn from NYC, as the average density is much higher than anywhere in the rest of the nation, and many people might not want their city to become the same. But this density and level of transit service will definitely give New York an edge in the looming world of Peak Oil.