According to this report from the BBC Tim Toulmin (director of the Press Complaints Commission) has said that Blogs and other internet sites should be covered by a voluntary code of practice similar to that for newspapers in the UK.
I cannot see how this would work in practice. Presumably those who sign up to it would be most likely to stick to it in any case and those who would not stick to it would not sign up. To say nothing of the fact that there is always the option for someone to sue for libel in any case.
This story is also covered here on Libertarian Home