What about a game menu? It would seem to me that those are as much an invitation to burn-in as a DVD menu.
I too wouldn't buy a plasma unless they were priced to be disposable i.e. a $1.00
I've played countless hours of gaming via my xbox for over three years (and a Wii). Many games have static menu items during game play. Still, no burn-in. Maybe certain manufacturers are prone to burn-in than others, but I don't have any after years of using the TV.