1 – Mobile is the first personal mass media (even the internet is only semi-personal).
2 – It is the first always carried media.
3 – It is the first always on mass media.
4 – Mobile is the first mass media with a built-in payment channel.
5 – It is the first media device available at the point of inspiration. And 6 – mobile is the first mass media with near-perfect audience information.
I think I’ve blogged about this before, and if not – I should have. This blog entry explains more, and you should be reading the whole blog regularly.