An April 2009 survey by the Pew Research Center's Internet & American Life Project shows that 56% of adult Americans have accessed the internet by wireless means, such as using a laptop, mobile device, game console, or MP3 player. The most prevalent way people get online using a wireless network is with a laptop computer; 39% of adults have done this.
The report also finds rising levels of Americans using the internet on a mobile handset. One-third of Americans (32%) have used a cell phone or Smartphone to access the internet for emailing, instant-messaging, or information-seeking. This level of mobile internet is up by one-third since December 2007, when 24% of Americans had ever used the internet on a mobile device. On the typical day, nearly one-fifth (19%) of Americans use the internet on a mobile device, up substantially from the 11% level recorded in December 2007. That's a growth of 73% in the 16 month interval between surveys.
Read the full report Wireless Internet Use on the Pew Internet & American Life Project's Web site.