Mar 17, 2011 10:01 GMT  ·  By

If there was any ambiguity about whether Facebook would be enforcing its effective ban on Google's AdSense in Facebook apps, it's gone now, developers have started being told to drop the Google ad network or face being excluded from the platform.

Many developers had already switched, since it was almost certain that Facebook would be moving to exclude ad networks that are not on its list of approved partners.

But some were not sure what Facebook would do and continued to use Google AdSense, and presumably other unapproved ad networks, as they have had so far.

Facebook is now reaching out to those developers and notifying them that they should start switching to approved providers. While the competition for app ad networks is much stronger, especially on Facebook, AdSense is still preferred by many.

They may already be using AdSense on their sites and other apps and prefer to have a single account to manage their ad revenue. AdSense also offers one of the best contextual ad technology and somewhat better quality ads than other networks.

But there's little chance of AdSense being approved by Facebook, though neither company would comment specifically on the matter.

Facebook announced that it would start requiring developers to choose only from a list of approved ad networks. The move was done to better protect user privacy, networks vetted by Facebook would be more likely to behave properly or lose their approval.

Earlier this month, the new policy went into effect. Google's AdSense was not on the list of approved ad networks at that time. Since then, 28 more providers have been added for a total of 72. Google is not one of them.

Facebook has every incentive to keep Google out, the social network wants to compete with Google on every level, especially when it comes to ad money. So far, Google has stayed quiet and it looks like developers will have to start looking for alternatives.