Google’s acquisition of mobile ad network AdMob, a deal big enough that the Federal Trade Commission investigated it as a possible monopoly, was cleared and closed last week. Now, AdMob has released a software development kit that lets publishers include Admob-served ads on all iPhone OS devices — iPhone, iPod Touch, and iPad.

Google and Apple, once cozy partners, have grown increasingly competitive in the past year. Yet Apple’s clout is such that Google is going out of its way to ensure its products work on Apple’s products, even if that means creating Apple-only software and content.

The trick to AdMob’s new iPhone OS kit is that, while it produces Apple-only output, it accepts the same inputs as ad tools for other platforms. There are two forms of ads available: Text ads of up to 35 characters, and image ads in industry-standard sizes such as 300 x 250 pixels, or a superwide 728 x 90 pixels on the iPad.

AdMob has produced both screenshots and a video demo to show what’s possible on the iPad.