Ad network revenue shows iOS and Android are almost tied

A monthly report from Mobile ad network Millennial Media paints a familiar picture of the smartphone market. According to impressions data, the iPhone is the top individual phone on the ad network, while the iPad is on the rise with a 29% jump in impressions from last month. Apple was the top manufacturer with a 30% impression share.

On a platform basis, Android was the leading smartphone OS with a 53% impression share, while iOS was a distant second with a 27% impression share. Rounding out the platform listing is RIM at 17%, Symbian at 2% and Windows Phone 7 at 1%.This impressions data reflects the number of times an ad is viewed.

Ad revenue from apps paints a different picture than the impressions data. In ad revenue, iOS and Android are neck and neck. iOS had a slight lead with 45% share, while Android had a 43% share. RIM grabbed 9% of ad revenue, while the remaining 3% is picked up by other platforms.

iOS is holding a slight lead over Android, but the green robot is closing in fast. In April, iOS was at 50% and Android was trailing with a 39% share. In May, that gap narrowed, and the two platforms may trade places in June.