From the other thread:
Ryan Gosling is a genius choice for Hal Jordan. He's a brilliant actor, one of the best of his generation. Putting him in the leading role does the same thing as casting Christian Bale as Batman or Robert Downey Jr as Tony Stark. It's showing that you're taking the film seriously, by casting a legit actor in the leading role. Gosling is a valued asset to any film he lends his services to, and whether or not he accepts the role, the fact that WB are going for actors of his calibre tells me they want to go about "Green Lantern" the right way.
I have said repeatedly that the filmmakers are probably going to go for a guy who's good enough to headline the film, so it isn't going to be a TV star or a lesser actor who happens to have the brown-haired, square-jawed Hal look. Gosling might not look exactly how we picture Hal, but he's got the talent to capture the spirit of the character and bring him to life for a wider audience. And he's one of these actors known for putting on/losing weight dramatically, and transforming for a role. I'm sure by the time shooting comes along, if he's cast, he'll be utterly convincing as Hal Jordan.