Guess it's not that much of a nutty idea.
Now because it's New York, it's instantly taken more seriously because it's New York and everything is taken more seriously there (damn East Coast bias). In a way, it’s kind of like Jamba Juice--everyone thought it was some crazy only-in-California idea and now they're everywhere. Already, the New York Times has jumped in and said it's a fabulous idea and the New York Post, not known for it's liberal ideas, thinks it's well worth considering. A poll was also taken earlier which said that a majority of people in the city support it and just from comments on Gothamist, it looks like readers are in favor.
The idea, called congestion charging, was actually proposed a year ago but is now being championed by Mayor Mike. The idea is to charge commuters $8 ($21 for trucks) for driving into Manhattan and people could pay for it using the EZTrak system or their license plates could be photographed and sent an invoice. The whole plan is expected to bring in about $500 million annually into the city's coffers which would be used to help finance transportation related issues.
Here in SF, the idea is being studied and the results of the study should come out, hopefully, sometime soon.