Google's recent announcement of their OpenSocial API's appears to be a new form of middleware for connecting social networks together. But it's too early to tell, since the technical details are not available yet. The notion of a middleware service for connecting social networks and sharing data between them makes a lot of sense, and if Google has really made it "open" then it could be very useful. The question remains of course, why would Google do this unless there is some way they have a unique benefit from it? My guess is that they will run advertising through this system, and will have unique advantages in their ability to target ads to people based on the social network profiles they can see via this system. We'll have to wait and see what happens, but it is interesting.
From the perspective of Radar Networks and Twine.com, this is a trend we are watching closely. It could be something to integrate with, but until we really see the technical details we'll reserve judgement.