I will be posting more on OpenSocial in the next week or so. I spent all last weekend working with it. It was a bit frustrating because a couple of the APIs weren’t working for me on Orkut. However, I feel like I got my head around it.
In the meantime this wiki is a good resource. Specifically, I’m keeping an eye on the “List of OpenSocial Containers” section at the bottom of the page.
Main Page – OpenSocial Directory: “List of OpenSocial Containers”