The new iGoogle ACLs allow users to explicitly grant or deny access to social data to their gadgets installed in their developer sandbox. “When OpenSocial gadgets are available to all iGoogle users, users must grant permission before gadgets are allowed access to social data. If a gadget is released without social features and is upgraded, users will be prompted for access within the gadget when the new version is first rendered.

Developers, this is important, so take note. If users deny access to social data, the gadget should have a good error message and graceful fallback UI,” informs iGoogle Blog.