Before today, Jason Collins was known as a 34-year-old center on the NBA's Washington Wizards. But after an historic public admission sure to redefine sexuality in sports, Collins has now become the first openly gay athlete playing in one of the four major sports in North America. As Collins writes in his cover story for this week's Sports Illustrated: "Things can change in an instant, so why not live truthfully?"

Collins's representatives got in touch with SI's Frank Lidtz for a story with quite the backstory — even Jason's twin brother, Jarron, who starred with him at Stanford, was caught by surprise. But Jason Collins seemed to know what kind of week he's about to have — he played a relaxing round of golf Sunday morning before the entire world started to call him about the coming out:

There have been rumors swirling that a handful of players from the NFL were set to come out sometime this summer while that league was struggling to deal with same-sex acceptance. Getting ahead of the pack, the NHL made a deal with YouCanPlay, a group advocating sexual equality in the locker room, to help bring the hockey league to forefront of same-sex acceptance in sports. But the NBA just leapfrogged them both by becoming the first league with an out athlete. Let the media storm begin, and may the NBA hold up under the pressure. As SI's Jon Wortheim makes clear, this is a big deal — a bigger deal than it should have to be, maybe, but the beginning of something big:

At some point the idea of having no openly gay athletes in a league might sound as unimaginable as a ball field segregated by race. But today Collins becomes the first active male athlete in a major U.S. team sport to come out of the closet. Yes, that's a lot of qualifiers. Yes, it may be an artificial construct. But it is a milestone.

Update: The reactions have arrived, and there are good and bad signs all around.

Update No. 2: The NFL is preparing, and cracking down.