Asus used to make an interesting 3-in-1 that fit into the marketplace there (unfortunately never released in the US). It was basically a zen phone that you could slide into a dock in the back of a tablet for a bigger screen and more battery. Then you could snap that tablet into a keyboard dock with even more battery.
It's just a shame the phone was only around midrange. I could imagine something like that being appealing for gaming on the go.