According to 'Kong is King', 'The Hobbit' is pencilled in for the summer of next year. Peter Jackson has a lot on, it seems, with Dambusters being produced, The Lovely Bones scheduled for 2007 and Halo scheduled for 2008. However, it's only on 'The Lovely Bones' that he's directing/writing. With 'Halo' he has 'executive producer' credit, I think the same is true for Dambusters.
(1) given the obvious links that the KongIsKing site has to PJ, I don't think unsubstantiated rumours would appear there, even if they're presented as such