UFO enthusiasts are making Las Vegas their home base this weekend. The 7th annual UFO Crash Retrieval Conference will run today through Sunday with a variety of speakers and topics, including presentations on some of the most famous UFO cases through history. Still, the U.S. says it has not classified files on UFOs to make public, prompting conference organizer Ryan Wood to say the world shouldn't hold its breath waiting for the Pentagon to come clean. The gathering will be held at the Tuscany Suites and Casino on Flamingo Road.