AdMob has released their network data report for March, 2009. The report shows that worldwide requests on the AdMob ad network grew 17% from a month earlier to 7.7 billion.

The report takes a detailed look at the growth of Android based phones, and also reveals that 50% of all ad requests from iPhone and Android devices come from applications!

Overall, Android represented about 6% of the total ad requests on the AdMob network, and is now tied with Palm as the #4 mobile smartphone OS in the US, behind iPhone, Rim, and Windows Mobile. The G1 is now the number 4 smartphone in the US trailing the iPhone, Blackberry Curve, and Blackberry Pearl.

In terms of comparing overall growth rates, the iPhone requests in fact grew much faster initially than Android requests: Android grew 47% per month since launch, and iPhone grew 88% per month since launch of the App Store. However, both of these grow rates are significantly faster then the market overall.

Looking in more detail at where the ad requests come from, AdMob says that more than half of the ad requests for iPhone and Android come from applications, rather than mobile web pages. And there is a wide variety of applications being used – in addition to the games category which would be expected, there are also movie apps, news apps, and sports apps.

AdMob’s conclusion is that this is an indication that application stores on platforms other than the iPhone can be successful, and that apps are likely to continue to replace some browser based activities.

The AdMob report also includes more detailed data on the US, Indian, UK, South African, Philippine, and Indonesian markets. Here is some information on the worldwide ad request growth, and the South Africa smartphone market.