This. Facebook has a problem on mobile devices. A great number of users use them but the real estate for advertising is greatly diminished. I wouldn't be surprised if in the next iteration, ads of some kind will pop up. In fact its probably the entire reason for this project.

You can see an example of it on their page even: http://static.ak.fbcdn.net/rsrc.php/v2/yY/r/fNNR8sV8Y3W.png

Facebook is some form of advertising. So don't be skeptical, be certain.

No need to be skeptical, Facebook has already said they will put advertising on your home screen (it was a question from the press.)

"Keep receiving our ads, even when you're using other apps." ;)