Smartphones based on Google's Android operating system racked up 53 percent ad impression share, shaving share from Apple's iOS, according to ad platform Millennial Media.
Millennial, which is reportedly mulling an initial public offering, said Apple's iOS netted 28 percent of ad impressions in April, down from 31 percent in March. Research In Motion's BlackBerry took the No. 3 slot with 16 percent.
There is a bit of turn-about-is-fair play here. Android, which landed 16 of the top 20 smartphones by impressions, essentially took back share it lost to iOS in March, when it fell to 48 percent share. Millennial attributed the loss to the launch of Apple's iPhone 4 on Verizon Wireless.
While Android gained in ads and sported a 52 percent hike in applications, iOS still ruled the roost in revenues.
Easily 50 percent of revenues came from iOS apps, compared to 39 percent from Android programs. Apple's iOS revenue grew 6 percent in April from March.
Gaming apps, of course, led the way with 32 percent of app impressions. Travel apps ratcheted up 91 percent as people research their summer vacation plans.
In a sign that bodes well for those publishers and developers who want to run ads on tablets, impressions on Web-enabled mobile devices, such as the iPad, iPod Touch and Samsung Galaxy Tab, grew 200 percent from the fourth quarter 2010 to Q1 2011.
With several more Android tablets, RIM's PlayBook rolling out and HP's TouchPad all flooding the market this year, it will be interesting to watch the progress of connected device ad share.
Millennial's latest mobile market report comes as the ad provider is allegedly girding for an IPO. Millennial is the largest standalone mobile ad provider after Google acquired AdMob for $70 million and Apple purchased Quattro Wireless for an undisclosed sum. ValueClick just bagged Greystripe.
Bloomberg said Millennial could go public for between $700 million and $1 billion.