In terms of the iDevices, what's surprising is the lack of operating system fragmentation with 95 percent of the devices tracked by AdMob's mobile advertising network running OS 3.0 or higher.
This will be an over estimation as people using devices running the older OSes are less likely to be tracked by this method, but it's still an impressively high number.
Breaking down the hardware types sees a great spread however.
Four percent of devices tracked were the first generation iPhones and iPod touches, while 45 percent were either the iPhone 3G or second generation iPod touch.
Just over half the activity in the iDevice ecosystem comes either from iPhone 3GS or iPod touch third generation, with the 3GS being the most popular single device with 39 percent of the market.
In total, AdMob received 6.1 billion requests from iPhone OS devices in March, compared to 7 million for Android.
Three-way split
When it comes to Android OS fragmentation, the picture is more divided. This is because handset manufacturers and carriers can limit the ability of a device to update to the most recent operating system.
For this reason, activity is split fairly equally between the three Android OSes.
Android 1.5 has 38 percent, Android 2.x (particularly driven by Motorola's Droid) is at 35 percent, while Android 1.6 has 26 percent.
You can get the full March report in PDF form from the company's website.
[source: AdMob]
