Earlier rumors included David "Angel" Boreanaz, Seth "Robot Chicken" Green, and Justin "Mac guy" Long. None of which (except maybe Boreanaz) seemed like a good fit for protector of sector 2814.
The Ryan Gosling rumor has come from
Latino Review, who has a good track record of being right with past rumors. Apparently they have an unnamed tipster working at Warner Bros who has slipped them the information. Time will only tell if Gosling is actually offered the part, and then he'll still have to accept the role--all of which makes for too many variables to be sure.
The script has reportedly been turned in, met with approval, and given a 2009 start date.