It seems like Facebook is aiming to become your portal to the world. The increased functionality and embedded applications available in Facebook make it easier to accomplish your web related tasks without leaving the portal.
I think it’s still a long way off, but more sites are developing facebook apps that allow you to stay with your FB page. For instance, here’s an article on Zipcar:
and more apps are coming each day. I think that more websites and businesses will have to develop facebook related apps to allow users to seamlessly move between sites and applications, without logging in again.