What a strange world we live in, where the dominant players in an industry can literally flip-flop overnight with the underdogs.

First, the FTC approves Apple’s acquisition of Quattro Wireless without even blinking, so that it could enter the mobile-ad business, then meanwhile it makes Google (NSDQ: GOOG) wait months for approval to purchase AdMob. And now, just weeks after citing Apple (NSDQ: AAPL) as the reason why Google can purchase AdMob, the FTC is now preparing to review allegations that Apple is engaging in anti-competitive tactics to restrict rivals in the mobile-advertising market.

People familiar with the matter told Bloomberg that the FTC and U.S. Justice Department had been discussing which regulatory body should conduct the investigation.

Spokesman from either Apple or the FTC declined to speak to Bloomberg, however, the central issues appears to be whether recent actions taken by Apple will result in less competition in the burgeoning mobile ad market.

This week, Apple banned mobile ad networks, such as Google’s AdMob, from collecting information like a person’s location to provide more relevant advertising. The move prompted AdMob’s CEO Omar Hamoui to write a blog post, saying that Apple is being anti-competitive: “The terms hurt both large and small developers by severely limiting their choice of how best to make money. And because advertising funds a huge number of free and low cost apps, these terms are bad for consumers as well,” he wrote.

The way Apple wrote the terms doesn’t seem to preclude most ad networks from collecting data, just mostly companies that also have a mobile handset business, like Google, or potentially Microsoft (NSDQ: MSFT) or Nokia (NYSE: NOK).

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