New York Times: When New York Mayor Michael R. Bloomberg unveiled his sweeping environmental vision for the city two years ago, the venerable American Museum of Natural History served as his setting, and Gov. Arnold Schwarzenegger of California and Tony Blair, then the British prime minister, piped in messages of support via two large television screens. Not to be outdone, this wealthy enclave 45 minutes north of the city rolled out its own stars on Saturday as it part of its ambitious plan for a …