AdMob is crowing that it's served up 20 billion ads, making it the first mobile advertising company to hit this milestone. The 20-billionth impression was from financial services conglomerate HDFC and was displayed on March 25 in India, to someone browsing Cricinfo's mobile Web site on a Nokia N70.

Other impressive stats from the mobile ad marketplace include:

-Since March 2007, the company's monthly impressions have grown from 500 million ads per month to 2.5 billion per month.

-AdMob has 40% market reach of US consumers with mobile browsing capabilities. That's a potential audience of 36 million in the US alone. The company serves ads in more than 160 countries on a daily basis.

-There are now more than 3,900 mobile Web sites using the AdMob platform.

The company also brought this interesting factoid to our attention: "Although AdMob competes most directly with Google and Yahoo, both titans are advertisers on the AdMob network. Ironic eh?"