This finding caught me by surprise. Study of US media consumption by Universal McCann revealed that already one in seven minutes of US media consumption is used with mobile. Now, note that this includes parallel use, so if we watch TV and vote on American Idol, we consumed both TV and mobile. But still, gosh. TV, radio, newspapers, magazines, and the internet - and mobile gets one in seven minutes of media consumption. Story was covered in Adweek.
Part of the answer lies in where mobile media is consumed. 82% use mobile phones to consume media at work (ie listen to the MP3 player for example) and 65% while commuting. Here TV has almost no chance to contest for that time and other media also probably less easy to consume except web at work and radio while commuting (print perhaps also as long as you are not driving..) So mobile has some time slots where it has few rivals. But yes, every one in seven minutes. Easy to memorize, one in seven for the 7th mass medium?