New York City could be considered the Big Green Apple for the rest of the week. Bill Clinton and Mayor Bloomberg are hosting an international climate summit this week, beginning today and running through Thursday. And as part of other environmentally friendly festivities, Matt Dillon was on hand for the issuance of a challenge from Yahoo! to see which U.S. city was the most green.

The winning city, that will be announced following the program's conclusion on June 8th, will be rewarded with a fleet of hybrid taxi cabs or the equivalent cash donation, to be dedicated toward city greening projects. To kick off the program, Yahoo! will also donate a fleet of hybrid taxis to New York City, which recently determined it produces 1% of all U.S. greenhouse gases. By displacing traditionally fueled cabs with hybrid taxis, Yahoo! will be helping New York City edge closer to its ambitious environmental goals. The City will also save enough gas to drive a hybrid vehicle 56 times around the Earth.

So NYC has already won, we've got a fleet of hybrid taxis! The theory behind the meeting is that, despite cities' lack of methane-producing farm animals, they still need to take a leading role in reducing greenhouse gases. David Filo, co-founder of Yahoo!, posed with Matt Dillon and urged cities and individuals to act as responsible "planetarians", which we will also encourage, despite our inability to find the term in a dictionary, but we all get the point.

Yahoo!'s green-focused site is here. The governmental and business alliance to halt global warming is called C40. And Representative Anthony Weiner feels the problem isn't cars, but trucks. Has anyone taken a ride in a leafy green taxi yet?