During the last year, the number of mobile Internet users in the U.S. has doubled to 22 million people. At the same time, according to dotMobi data, the number of mobile-friendly Web sites has quadrupled.

The mobile-friendly Web is now serious business – and a lot of companies are realizing they’re not prepared. That could be costing them money, as the demographics of touch-screen phone owners (such as the iPhone or Blackberry Storm) are alluring to advertisers, since they usually boast higher-incomes than ‘dumb phone’ users.

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