If any signals are received and understood, this would eclipse Man on the Moon, and become the most monumental discovery ever. Then there are those, led by Erich von Daniken, who insist aliens have already been here, left obvious evidence, and, like ET, left for home. Some cite the Mayan culture as an indicator, and, just wait till 21December2012 when, maybe, they could return.
Carl Sagan, however, had the right attitude. His Contact, made into a movie with Jody Foster, remains one of my favorites.