While at Sony in 1994, I was sent to Virginia to learn how to build a Sony "app" on AOL (the #3 online service, behind Compuserve & Prodigy at the time) using AOL's proprietary "rainman" platform.
Fast forward to Facebook 2007 and see similarities: If you want access to their big base of users, develop something in their proprietary language for their people who live in their walled garden.
