Awesome review Analyzing the Facebook Platform three weeks in by Marc Andreessen. Strategically, he outlines why Facebook is a real leap ahead. As a user that certainly has been my impression. The iLike story is a real nugget in his analysis with growth figures and the implications for scaling on Facebook. iLike went to two million users in less than two weeks and today reports 6 million.
They are quick to adopt the Skype chart on Viral growth. Truly phenomenal. In the iLike post they explain why we can't yet tie our Facebook accounts to our iLike accounts. It will be worth watching how this evolves. If you haven't add it to your Facebook page and keep an eye on it.
One thing surprises me about Marc's analysis. There has to be a business just in hosting apps / providing the infrastructure to scale Facebook. I'm sure some models will evolve or even Facebook could provide it as a service.