AdMob has released its March Mobile Metrics Report, with a special focus on the Android and iPhone platforms.

According to AdMob, in the five months since the Android Market for applications launched in the US, requests from Android devices increased an average 47% per month. As good as that sounds, it's nothing compared with the traffic generated by iPhone; in the first five months after the iTunes App Store went live in the US last July, requests from the iPhone grew 88% per month.

Still, the T-Mobile G1 (HTC Dream) now claims 2% of the US market, based on traffic over the AdMob network. In March, it ranked 10th overall in the US and was the fourth most popular smartphone, after the iPhone, BlackBerry Curve and BlackBerry Pearl.

AdMob's metrics are based on requests for AdMobs across the mobile Web and in mobile applications.

For more in-depth comparisons of Android v iPhone as well as other metrics, you can access the full AdMob Metrics report for March here.