by Mark Walsh

Google’s proposed $750 million acquisition of AdMob looks at first glance like a move sure to extend its online ad dominance to the mobile realm. But Google isn’t the first major Internet player to gobble up a mobile ad network to gain an early advantage in the space. In 2007, AOL bought Third Screen Media and Microsoft acquired European-based mobile ad company Screen Tonic.

As with Google’s bid for AdMob, analysts hailed the Third Screen purchase as a validation of mobile marketing efforts. But neither the Third Screen or Screen Tonic deals have made AOL or Microsoft the giants of mobile advertising. In the case of Third Screen, the departures of key executives including founder and CEO Tom Burgess following the acquisition probably didn’t help the company sustain momentum.

“You have to find a way of keeping key personnel at these companies or finding people who are roughly as capable,” noted Roger Entner, senior vice president and head of research and insights for the telecom practice at the Nielsen Company. “AOL bought Third Screen Media and everyone left.”

Both Google and AdMob have assured that won’ t happen following the closing of their deal. “Attracting the world’s top engineering talent and people with entrepreneurial vision to Google has always been crucial to our success,” said Vic Gundotra, Vice President of Engineering at Google.

And for his part, AdMob founder and CEO Omar Hamoui in a blog post yesterday wrote: “The best part of all this is what’s next. We are not going away.” Time will bear out whether he keeps that promise.

Entner said he expects the Google-AdMob deal more of the big traditional Web companies to pursue mobile acquisitions to keep pace. But he stressed that simply snapping up a promising mobile startup doesn’t guarantee success. “You have to execute very well,” he said. “[Mobile] is a vibrant, ongoing engagement, so you have to keep working at it.”

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