As we've mentioned in our Lionhead News a couple of weeks ago - http://www.lionhead.com/?newsid=35 - everyone had the opportunity to ask Peter Molyneux a question. You can find his answer to the first ten question on GameDaily: http://www.gamedaily.com/articles/features/10-questions-lionheads-peter-mol....
"Peter once again answers your questions. He estimates Fable II could have up to 100 hours of gameplay, he likes the idea of PvP (perhaps as DLC?), and he hasn't ruled out creating another Black & White. Much more within..."