AdMob serves ads for more than 7,000 mobile Web sites and 2,500 applications around the world. AdMob stores and analyzes the data from every ad request, impression, and click and uses this to optimize ad matching in the network. This monthly report offers a snapshot of the data to provide insight into trends in the mobile ecosystem.

Five days after its launch, the iPhone OS 3.0 represented 44% of iPhone ad requests. In contrast, only 1% of iPod touch requests came from devices running the iPhone OS 3.0.

Worldwide, Apple iPhone’s share of smartphone traffic hit 49% in May 2009, up from 43% in April 2009:

In the U.S., Apple iPhone’s share of smartphone traffic hit 69% in May 2009, up from 59% in April 2009:

These numbers, of course, predate the release of Apple’s iPhone 3G S which was released on June 19, 2009.