All porn is child porn
All online porn is child porn unless you can prove otherwise
is what The Register are reporting on the new US law that has been extended to cover websites and other new media.
The law essentially places the onus on operators and suppliers of Adult content to prove that the participants are of legal age. By default this means that without proof of age, an operator of an adult site will be held and considered a child pornographer.
It won't matter whether your site caters for "Old Grannie loving" or "MILFs" as proof of each of the participants in acts will be required to be shown.
Sites have already taken themselves offline as they do not have the required proof. Some of these sites are not pornographic in nature but may have adult pictures within their whole.
The full text of the legislation is available from Cornell University