InMobi presented a Mobile Insights Report in which the numbers show us that almost 4 out of 5 ads are now delivered on smartphones, especially inside applications in North America.
According to this report Android still leads in the 2nd quarter of 2011 with 33.2% of mobile ads, while iOS follows pretty close with 29.3%.
Top 3 Operating Systems:
Q1 2011 // Q2 2011 Points Chage
Android: 37.2% Q1 to 33.2% Q2 -4.0
iPhone OS: 18.3% Q1 to 29.3% Q2 +11.0
Remaining OS: 44.6% Q1 to 37.5% Q2 -7.0
You can get the full report for free from InMobi by clicking here (requires registration).