Well, a few would have vendettas or 'evil' things they'd like to do right off the bat. Most, I would think, would feel alienated and that could lead to all sorts. A few would use their powers in everyday life and impose justice as they see fit (I know that's what I'd do). But what it amounts to is a very large percentage essentially dicking around, with maybe a couple joining the police force or military or something. Not to mention there'd be infighting among the superpowereds, aliances could form later. The governments of most countries would get involved, trying to restrain, regulate, maybe kill them, a few would be killed and the rest would be split into a handful of "let's negotiate"s and the majority I would think going for the "screw governments" approach. Essentially, a cross between Chronicle and X-Men.
But what do I know, I haven't seen it happen.