The smartest thing to do would be to convert all of facebook's APIs to OpenSocial over the course of six months, do it before anyone else does (i.e. MySpace), help the developers keep their apps working the same, and just keep on trucking.
What hype? Google's announcement barely splashed in the world. I only know anything about it because I have been following it. But my actual comment is that what you're seeing is the transformation of the closed data systems to the open ones, a transformation that FB started. But next, because of what facebook started and what Google is promising, we're going to see the change from using a 'social networking' site as a discreet home page or portal, to your own, and indeed all web sites, having social functionality that lets the data flow through. Security of my information is still a paramount concern of mine.