NASA press release:
"The Delta II rocket carrying the Kepler planet-hunting spacecraft lifted off on time at 10:49 p.m. EST from Launch Complex 17-B at Cape Canaveral Air Force Station in Florida. The spectacular nighttime launch followed a smooth countdown free of technical issues or weather concerns. The Kepler spacecraft will watch a patch of space for 3.5 years or more for signs of Earth-sized planets moving around stars similar to the sun. The patch that Kepler will watch contains about 100,000 stars like the sun. Using special detectors similar to those used in digital cameras, Kepler will look for a slight dimming in the stars as planets pass between the stars and Kepler.
COMMENT: This should be a great step forward for science. If we want to probe other worlds someday, Kepler is likely to give us much more information on the location and types of planets worth visiting. Until then, it will tell us a a great deal about how planets and solar systems form and under what conditions planets can survive.