We had the exact same problem after my 5 year old son watched "Finding Bigfoot" on Animal Planet! We have ended up leaving the light on in his bedroom, which believe it or not, he can fall asleep (I can't sleep with the light on!), and leaving his door wide open with the hallway light also on. We also let him sit or lay in bed and read books to himself if he wants, to help him get sleepy and take his mind off of "things." And we put on some music (an old lullaby cd that he loved as a baby, he doesn't seem to mind that it's "baby music"). All of this was explained as our "compromise" to being in the room with him, after explaining that he was a big boy who has been able to sleep on his own for some time now. It has worked remarkably well for us.
I should mention that there are nights he doesn't fall asleep until 9:45 or 10pm, and he gets up at 7:30. I saw Charles Fay from "Love and Logic" speak, and that's where I got some of these ideas. He says it's hard to force someone to sleep, that you should call it "bedroom time" not "bedtime" and let the kids get used to putting themselves to sleep. He feels that if they are staying up too late and therefore tired the next day, you can say something to the effect of "Are you tired? I know I feel tired when I stay up late too" but don't make the child feel bad or "I told you so" kind of thing. He feels they will learn that staying up late makes them feel bad the next day all on their own.
Like I said, these things worked for us. I wish you good luck!!