• July 9, 2008

With 15.6% of its mobile users actively using the Internet, the U.S. has reached a critical mass for mobile Web marketing, according to a new study by Nielsen Mobile.

Helping to drive mobile Internet adoption is the growing popularity of unlimited data packages, which 14% of U.S. cell phone users have signed up. Half of data users say they prefer the unlimited pricing model, according to the Nielsen report titled "Critical Mass: The Worldwide State of the Mobile Web."

The top U.S. mobile sites as of May were Yahoo Mail, with 14.2 million unique visitors, followed by Google Search (9.1 million) and The Weather Channel (8.6 million). More than a quarter (26%) of mobile Internet users view ads and overall are more receptive to advertising than average mobile data users.

Among other Nielsen findings, Motorola's Razr phones are the most popular among U.S. mobile Internet users, while Nokia handsets lead in Europe and Asia.--Mark Walsh