My personal management policy is I get in before and leave after all my employees incase they need me and to show them that I am there for/with them (within reason - if someone is putting a really late night I may leave first).
The idea of not leaving before the boss leaves is weird to me. I get higher pay and more stock options, why should I be leaving early when my team is working their butt's off?
Edit: I realize this could be taken as a ploy from me to get the team to work more hours. But I also don't shame employees for leaving before me. It's not a contest. If they get their work done they shouldn't feel guilty leaving at 5:00.