Here is an example, Hellboy. The game was finished nearly 9 months prior to its release, and could have been finished even earlier. However the studio wanted to wait to do a release with the new movie. The game now looks as though it could be on PS2. Very similar to God of War, in play style, but worse in graphics. This game could have probably sold better if it was released prior to it becoming a dated IP.
Same with Ghostbusters, I know we will all purchase it, but after October, a month were we are already thinking Ghosts, and goblins, and awesome frightening stuff, I cant see it being as big of a deal in the Spring. I think it will by then feel dated, and look dated.
As mentioned Fallout 3. Its something that I consider a must have, I enjoyed the first two, however the new console build makes it seem some what dumbed down, however we will see. And as for Fable 2, I will believe it when I see it. Not that I doubt you, but Peter Molyneux is a man of many words, and very few actions, though October does seem very possible. Fable appeals to a fairly large market of Xbox owners, but at the same time, I personally believe that a high profile game such as Ghostbusters would hit an even wider market.