Millennial Media generated 10 billion mobile ad impressions in the US during 1Q09, with 3.39 billion impressions in March alone.

The stats come from the company's inaugural Scorecard for Mobile Advertising Reach and Targeting (SMART) report.

Millennial says it's network is now reaching 31 million of the country's 56 million mobile internet users as defined by Nielsen.

Other factoids from the 1Q09 SMART report include:

-The top 20 handsets account for 43 per cent of all mobile web traffic on Millennial Media's network.

- 58 per cent of campaigns utilised some level of geo targeting.

-Ten of the top 20 US mobile DMAs by ad requests were in three states: California, Texas and Florida.

- 42 per cent of campaigns utilised frequency capping.

Click here to download the full report in PDF form.

Paul Palmieri, president and CEO at Millennial Media, said: "Mobile is real, has attractive reach, and is delivering the most cost-effective engagement in the digital advertising space. We are delighted to put a program in place to help advertisers understand the scale, value and growth of the mobile medium based on our observed network data."