What are the legal issues about being a surrogate in Australia for a male same- couple?

I have a good friend from high school, who I have known for years. He would make an amazing father, but he's gay. I'd be happy to be a surrogate for him in the future, but I'm not sure if that is legal in Australia. At the moment he's single but if he were in a de-facto relationship what are the laws that would allow or prevent it. In plain English would be great, I haven't swallowed a legal dictionary any time recently :P