The Gmail PHP SDK by Google currently in Beta stage includes authentication and authorization with Api Keys and OAuth 2 to start project development. Additional resources include building the client object, building the service object, calling an API, and handling the result.
Some may remember yfrog as the photo sharing service previously associated with Twitter. However, since Twitter's launch of it's own internal photo sharing service last year, Yfrog has been left worse for wear. Despite the effects of this, Jack Levin (ImageShack founder) has not accepted defeat and has bravely entered the social networking arena to meet the giants face to face.