Rose of Whitmore Farm at the Everedy Square farmer's market let me know that the movie will be played at Gettysburg, PA: Majestic on August 7. This will be a nice trip to Gettysburg and watch the so-much-talked-about movie. Also googling leads me to this page that shows all the movie theaters that are playing Food Inc. As Chelsea and SixGables commented on Shannon's posting, Shepherdstown, WV: Opera House Theatre is playing the movie. Other close-by locations include Baltimore, MD: Charles Theatre, Bethesda, MD: Bethesda Row Cinema, and Washington, DC: E Street Cinema.
It would be nice to see the movie here in downtown Frederick. I sent out an inquiry email last night regarding this - will keep you updated if I get a reply.