The US mobile internet now has a large and diverse enough user base to support wide-scale mobile-marketing efforts, and mobile web users are 60% more likely than data users to be open to mobile advertising, according to a report (pdf) from Nielsen Mobile.
Mobile internet has reached a critical mass as an advertising medium in the US. In May 2008, there were 40 million active mobile internet users - a fraction of the 95 million US mobile users who subscribe to the service but do not necessarily use it, and a smaller fraction of the 259 million wireless users who are mobile data subscribers:
clipped from: www.marketingcharts.com 
