I agree with you that CBS would eventually have to release the documents, if other other news organizations pressured them into doing so. But, I don't think that would have happened. The Bush/Guard/AWOL story is old news. It would not have drawn much attention if the bloggers hadn't pushed the story.
the white house released the docs to other news media so cbs wanted to scoop the competition by posting then first..if they didnt others would have.