While not a true convention, this exhibit sounds cool:
Quote Originally Posted by A science thingy
Star Wars: Where Science Meets Imagination is the first exhibit of its kind, combining costumes and props from all six Star Wars films with real-world technologies, video interviews with filmmakers, scientists and engineers, and two large Engineering Design Labs, where visitors can build and test speeders and robots. Visitors will explore prototypes, learn about the engineers and designers who are creating new technologies, and discover intriguing similarities between how scientists and filmmakers think.

SPECIAL ADMISSION INFORMATION: We anticipate VERY strong demand for the Star Wars: Where Science Meets Imagination exhibit. For more information, visit http://goto.californiasciencecenter.org/sw
I'm heading there in a couple of weekends, perhaps even in costume! (science centers give less mocking for nerdi-ness, so I hear ).