In a May 2009 Mobile Metrics report that was recently released, mobile advertising firm AdMob revealed that the iPhone and iPod touch now account for 69% of the U.S. smartphone traffic on its ad network. The figure is up from 59% in April and 50% in March. Worldwide, the iPhone and iPod touch now account for 49% of smartphone ad requests.

      In a separate report issued earlier this week, AdMob disclosed that 44% of iPhone ad requests through its network on Saturday, June 20th came from devices running iPhone OS 3.0, demonstrating significant adoption of the new operating system.

      Conversely, only 1% of iPod touch ad requests on that date came from devices running iPhone OS 3.0, signaling the chilling effect of the $9.95 upgrade fee on adoption rates. iPod touch users also have less incentive to upgrade from a feature-based perspective, as many of the high-publicity upgrades found in iPhone OS 3.0 are limited to the iPhone hardware.

      As always, readers should note that this data is from a single advertising source (albeit the world’s largest) and tracks ad requests, which is only one measure of wireless phone traffic. In fact, in a separate study of iPhone OS 3.0 adoption rates released this week, one iPhone developer saw up to 80% of its iPhone customers and 50% of its iPod touch customers using iPhone OS 3.0 by this past Monday.