Facebook's list of preferred advertisers went into effect Monday, and Google AdSense isn't on the list. This new list prohibits developers from making revenue from their Facebook applications via AdSense.
As of Monday, Facebook began limiting developers to only working with approved advertisers who agreed to sign off on 12 items making up Facebook's Platform Terms for Advertising Providers. Facebook told All Facebook:
"This is the current list of ad providers that have signed our terms that govern ad quality and data use, although more are being added every day. We currently have more than sixty of the largest and smallest providers on the list. This is a public and open agreement and new providers can sign at any time."
Developers must now decide whether to quit using Facebook's platform, change their ad provider, or face a potential ban. No reports yet of any developers being warned/shut down due to continuing to run Google ads.