If you wonder about that question, please read below the answer (by Knowledge at Wharton, free after registration) of Ray Ozzie (via Brian Hall):

 

"The guidance that we are giving the development community -- and the guidance that we use in-house -- is to look at applications through the following lens: When the business model behind that app means that you have to get it everywhere, we call that the "universal web application pattern." When the most important thing is the experience that the user has with that application and you might be willing to trade off the breadth of the web for the richness of that experience, we call that an "experience first pattern."

There's no hard line between the two, but there is some guidance there. It's clear that the ad-based model is a "universal web pattern." The whole business model says, "Pick a technology for building that solution that gets to every eyeball on earth.""

What would Ali Alpay say?

I love this article by Michael Parekh, via Yme. It illustrates very well how Facebook is a set of existing webservices combined in a clever way, enabling new technology and functionality. However: will it 'shift the world'. We'll see. Probably the old paradigm holds: we overestimate what can change in 3 years, but we underestimate what can change in 7 years.