AdMob ( — which stores and analyzes handset and operator data from every ad request in its network of more than 15,000 mobile web sites and applications — says that, in February, smartphones accounted for 48% of its worldwide traffic/

That’s up from 35% in February 2009. The strong growth of iPhone and Android traffic, fueled by heavy application usage, was primarily responsible for the increase, AdMob says. Although the share of feature phone traffic in AdMob’s network declined from 58% o 35% year-over-year, absolute traffic from feature phones still grew 31%.

Mobile Internet devices experienced the strongest growth of the three categories, increasing to account for 17% of traffic in AdMob’s network in February. The iPod touch is the top mobile Internet device and is responsible for a vast majority of this traffic; other devices include the Sony PSP and Nintendo DSi. Highlights from the February 2010 AdMob Mobile Metrics Report include:

° The iPhone OS increased its share of smartphone requests from 33% in February 2009 to 50% in February 2010.

° Symbian’s share of smartphone requests fell from 43% in February 2009 to 18% in February 2010.

° Android increased its share from 2% in February 2009 to 24%in February 2010.