Facebook has given developers that link to the social network with Open Graph a new way let let users play tag with their friends -- while also increasing exposure to their app. It's called mention tagging, and allows a user to link a friend in the text body of a message, and is not to be confused with action tagging, an existing feature which references friends only in story text. The option requires a deliberate action by the user, so the developer must implement a way to clearly show how to do that with an icon (as shown above for
