XING, European online business network has launched an OpenSocial-based Partner Ecosystem. XING’s partners are now able to create applications using OpenSocial v0.8 and then easily integrate those applications into the XING professional network. The applications’re firmly integrated into the core functionality of XING, using OpenSocial's People, Activities, and Notification services. The applications’re thus able to leverage XING’s “business graph” of connections between professionals to make the applications engaging and rewarding for XING’s users.
More info: XING Partner Ecosystem