If the How to Ask box on the right-side when asking questions on Facebook.SO can be altered from its Stack Overflow brethren, I propose something be added stating Facebook.SO is for questions regarding Facebook development, and not general Facebook-use questions. Perhaps something like this:
How to Ask
Is your question about programming Facebook applications?
Facebook Stack Overflow is for questions about developing programs for Facebook. It is not for general Facebook-use questions. Questions regarding Facebook use should be asked on our sister site, Web Applications, instead.
We prefer questions that can be answered, not just discussed. Provide details. Share your research. If your question is about this website, ask it on meta instead.
Of course, this might be a little long-winded for the How to Ask box. I would propose putting it in the FAQ, but chances are the users who ask these generic Facebook questions won't be reading the FAQ anyways. Maybe it should be added to the FAQ as well, just for good measure.