I wholeheartedly agree with Roger Olson's comment on this: ". . . how does being a physicist make Hawking an expert on metaphysical questions?" Indeed, it appears that Hawking is as misguided on the context of heaven as many other folks, including (sadly) a great number of Christians. For, heaven is not some place where one might find God's house - even though many metaphors use this imagery to help us explain that which goes beyond our ability to explain - it is, rather, a completely other dimension of reality/existence. Heaven is the experienced presence of God, which means that it has the potential to be anywhere and everywhere at any given time. It is the connection to his omnipresence.
Culturally speaking, we have heaven on the brain these days. Rob Bell has made a bunch of noise regarding heaven and hell, and we are also being assured by some kid that heaven is for real.
But I'm curious - will Hawking's comments create anything close to the firestorm which Rob Bell's (mostly unread) comments made? Probably not. I suppose that this is because the Christian community will write Hawking off, even though the world (who hasn't heard of Rob Bell) will take him seriously. This is the fruit of internal wars, and evangelicalism's commitment to treat our non-believing-neighbors better than we treat our believing-selves.
But, hey, y'know . . . so long as we got it right.