Google's Android platform has nearly caught up to Apple's iOS in application revenue on Millennial Media for May, according to the mobile ad network.
iOS accounted for 45 percent of the application revenue in May, while Android followed with 43 percent sales share. That marked a closing of the gap for Google, whose platform commanded 39 percent of application sales, compared with Apple's 50 percent figure in April.
Millennial expects Android's application revenue to rise with the proliferation of more paid applications on Android devices.
"We expect Android to start to steal share from Apple as developers start to create more applications for the Android platform to take advantage of the high volume of customers who have shifted to Android devices," Millennial noted in its June 15 Mobile Mix report.
More than 100 million Android devices have shipped, with over 200,000 applications available in the Android market and almost 5 billion installed at this point.
As in April, Android smartphones racked up 53 percent ad impression share. iOS corralled 27 percent impression share, down from 28 percent in April and 31 percent in March.
RIM grew 6 percent impression share from April to hit 17 percent, thanks to a boost of impressions from the BlackBerry Curve on Millennial's network. Windows Phone 7 impressions grew 92 percent from April.
However, this isn't saying much as phones based on Microsoft's vaunted new mobile OS accounted for only 1 percent of the smartphone OS mix on Millennial.
Impressions for connected devices are up 190 percent from last year, prompting Millennial to count connected-device impressions for the first time.
MP3 players or mobile-gaming devices accounted for 70 percent of impressions on connected devices, followed by the iPad with 29 percent growth month-over-month, and 1 percent for e-readers and other machines of their ilk.
As for individual devices, the iPhone maintained its position as the top phone on Millennial, sporting a 30 percent share.
Samsung is No. 2 with 13.5 percent share on the strength of its Galaxy S phones, followed closely by RIM at 13.3 percent and HTC-which, with 11 percent, took fourth place from Motorola Mobility on the network.