InMobi has reported that impressions on its mobile ad network increased by 12% in Q1 compared to Q4 2011, up to 9.5bn in total.
Apple's iOS maintained it dominance over Android and RIM OS with a 45.7% share of available impressions, though this was actually down 2.7% on last quarter.
Android now accounts for 26.1% of mobile ad impressions on the InMobi network, an increase of 4% on Q4.
The top three devices in terms of ad impressions are also Apple devices, with iPhone accounting for 26.7%, iPad 11.9% and iPod 7.1%.
But despite InMobi's statistics (which can be seen in full in an infographic at the bottom of this post) there are signs that Apple's iAd is not as dominant as it appears.
In February Apple responded to declining marketshare by slashing its cost per campaign from $400,000 to $100,000, down from a whopping $1m when it first launched in 2010.
It also removed the additional fee that marketers were forced to pay when a user clicked their ad.
Google's fees for its AdMob platform also shifted to an AdWords-style auction, where the winning price is determined by the quality of the ad and the other bids on that impression.
It's clear to see that mobile ads are going to continue growing as a revenue stream, with data included in Econsultancy's Internet Statistics Compendium revealing that mobile ad spending in EMEA will reach $2bn by 2015, putting it on par with North America.
Furthermore previous InMobi stats show that smartphone ad impressions on its network increased by 488% in Q4 2011 compared to Q4 2010.
So it's no wonder that Apple and Google are willing to cut costs in order to secure market share.
David Moth is a Reporter at Econsultancy. You can follow him on Twitter.