It is possible, but rare.
The guy has to be mature enough to treat the girl as a friend, and the girl has to do likewise. Of course, there is a possibility that attraction will happen, but if the guy is mature enough, he can either pursue it, or let it go for the sake of the friendship.
Most guys are too immature and too prone to idolize sex to have any good cross gender friendships, and that is really sad. I have changed my mind about this a lot since college. I used to think it wasn't possible, but now after having some good friendships of my own, and growing up a bit, I see that close cross-gender friendships can happen. There are definite boundaries you cannot cross in what you share, but that just takes maturity (which like I said before, is quite lacking in today's culture). It definitely takes maturity on both side though (girls can act very immature themselves though, but it usually manifests itself in different ways <insecurity> ). I am lucky to say that I actually have 2-3 very good friendships with mature girls, but mainly I have mostly guy friends.