Just to add to my comment on mobile users versus internet users there are a few key things to keep in mind. First, mobile adoption has occurred much faster than Internet adoption in the last 5 years. Second, mobile penetration occurs to a much greater extent in underdeveloped countries where Internet access isn’t available or is quite costly. Compounding this is the cost of the access device: Computers range from several hundred to several thousand $US while cell phones can be purchased for much less (sub-$100 US) making them much more affordable. The chart  below shows approximately 250 million cell phone users in 2007.

In the US penetration for cell phones is pegged at 82.4% as can be seen here.

Related posts:

1. Mobile Subscriber Usage – US & Europe
2. The Age of Internet TV
3. Alignment and Execution