Apple is hosting an iPhone developer event Thursday, where they’ll most likely talk about adapting to the iPad—and a new mobile advertising platform. While I’m sure the developers and Apple are pretty excited at the prospect of more money, it’s Google that might be cheering the loudest.

Once upon a time, the two companies were friendly, but especially since Google has entered the mobile phone market, the two have become rivals—and that’s exactly why Google will be excited to see a new ad platform from Apple. After Google announced its acquisition of in-app ad platform AdMob in November, they’ve faced scrutiny from consumer groups and the FTC, especially since there appear to be few rivals for

Google has been applauding Apple’s recent advertising moves, from Apple’s acquisition of Quattro Wireless in-app ad platform in January. Quattro is likely part of the pending ad announcement. Google lauded the deal on their public policy blog.

But they’re not just genuinely good-hearted. Their true motivations are obvious from that January post:

When we announced our planned acquisition of AdMob in November, we noted that the mobile advertising space is highly competitive — with more than a dozen mobile ad networks.  In fact, the experts at MobiThinking recently called mobile advertising a “very fragmented” space, in which “no ad network is dominant” and “no one really knows what ad network is biggest.”

Today’s news that Apple is acquiring one of AdMob’s competitors, Quattro Wireless, is further proof that the mobile advertising space continues to be competitive.  And with more investments and acquisitions in the space, including from established players like Apple and Google, that’s a sign that vigorous growth and competition will continue. That’s ultimately great for users, advertisers and publishers alike.

If Google cna prove the FTC that the marketplace is highly competitive—and another major player in the space would help with that—then their acquisition of AdMob is all the more likely to get the green light.

What do you think? Will Apple announce a new ad platform? Will the FTC okay GoogleMob?