To clear up any confusion....
Everyone is, naturally, held up at the admission gate until time for the gate to open. Once the Star Spangled Banner finishes playing on the public address system, the gate is opened, and people can queue up and walk through the gate with their tickets.
Once through the gate, the entire park is open. There is none of this silly "let's rope off the back half of the park so that we can see a stampede at 10:00am" that we see in so many other parks (P*, BG*, SF*, etc). Typically, ride queues are NOT open when the park opens, so if you want to get in line for your favorie ride, you go to the queue entrance and line up there...then when the ride is ready, the queue is opened and you can wander through the maze.
--Dave Althoff, Jr.