What does the BBC know?

Tory Blogger Iain Dale reported earlier this evening that "the government (or maybe it's the Labour Party) has tonight taken out an injunction against the BBC to prevent the reporting of something substantive regarding the Cash for Honours Inquiry".

Now, the BBC confirm that the Attorney General has obtained an Injunction against the BBC reporting a story they claim is "in the public interest".

So just what does the BBC know? Who does the injunction really protect?