After looking I did come accross this post on the facebook forums:
link
They are feeding the facebook object a UIImage. That seems logical, but where is thi
Graph Api documentation of Photo upload are follows..
https://developers.facebook.com/blog/post/498/
https://developers.facebook.com/docs/reference/api/photo/
And you can see how to do this in iPhone here.
http://www.raywenderlich.com/1626/how-to-post-to-a-users-wall-upload-photos-and-add-a-like-button-from-your-iphone-app