Went by this morning, it is VERY board game focused. They are only running 1 D&D event each on Saturday and Sunday. Nice little store of used and new games for sale, but again almost everything was board games, NO RPGs at all, though they did have several Cthulhuian board games. Nice game library you could just pick up a game from and play at an open table. This apparently is their first one in the Northern Virginia area, as opposed to the usual spots in Maryland.
I think it's just what people make it, so if anyone wants to submit to run events I think they'd be happy to have you, just not sure how much interest there is in RPGs as I wasn't there when the D&D was running. But yes, the Rockville ones will have CoC!