Be careful. Malcolm Gladwell is full of shit. At best he writes pseudoscience. If you're looking for some sort of general introduction to nonfiction, there are probably a hundred thousand books you should read before you start in on Gladwell.
i just finished a Psychology degree and before I started it I really liked Malcolm Gladwell and thought he was spot on, but to be honest a lot of the pop Psych I personally find unconvincing. It's kind of like they've been made to dine out on. They're interesting but I don't think very scientific. Do still quite like them though I guess. Just while I'm commenting, OP my favourite nonfiction book I've read recently was Guns, Germs & Steel - but I think it might suffer from the same sort of thing I was just talking about.
I guess it was inevitable Jared Diamond show up in this thread. Similar to what I said about the Selfish Gene (though the authors aren't remotely on the same level) -- if all you read is Guns, Germs and Steel, you'll have an incomplete picture of cultural anthropology and so on. Back when I read it I also read scientific reactions to it; not pretty. w/e