I was there today - I had the intention of seeing "Where the Wild Things Are" with my two kids. Not now!
The signage was small - about 2 inches long by a half inch tall - it had the circle-slash and the verbage "No firearms allowed." This is part of a sign (printed on regular 8.5" x 11" paper) on the left side window of the front external ticket booth.
Because of the size and verbage, I do question the legal weight it carries, however, their intent is now known to me, and I do not patronize establishments that do not want me there.