Well if second screen is not available for 360/PS3 that's another reason to get next gen. Is it a next-gen selling ploy? Maybe. Live Maps for Halo were available 2 years ago so it has to be possible.
That being said, 360/PS3 players will be on more competitive levels with each other since no one will have a tablet with a live map sitting next to them.
I can't think though of a single elegant Apple-esque means to put a tablet in a location that is viewable at a glance.