Google's OpenSocial API Explained

Most of you might have heard about Google's Social Networking API OpenSocial. Rocketboom has a very easy to understand explanation of what it is: I think it's a good idea - especially because both Xing and LinkedIn are supporting it (who didn't wish that you could share your contacts between those two sites?). On the other hand it's a little scary that even more data about the user is being collected and shared.