Reader Timmy discovered that Major League Baseball's Seattle Mariners' official site lists their June 12 game against the San Francisco Giants as "STAR WARS Night". No other information is given.
UPDATE: The Seattle Star Wars Society apparently had a hand in planning the event. According to their site, "there is a Special Seattle Star Wars Society Discount and section... There is going to be a HUGE costume contest with some MAJOR prizes sponsored by Pepsi so come dressed up."