I saw a guy a few weeks ago on an evening train in Tokyo watching a ballgame split-screen with his email app, where he was writing a reply. He sent the mail, and then the TV app went back to full-screen. I don't watch TV, but that was just amazingly cool.

A year ago or so at a mid-scale sushi restaurant some guys sitting nearby were watching the ballgame on their phone, though thankfully they had the sound off.