I pretty much agree with Atrios on this re: Zakarias.
The thing is, on this blog for eight years (EIGHT FUCKING YEARS, OY!) I make a lot of snide little asides and plays on words. It is a style, but it is a style that I'm convinced at least several million people share -- probably far far more. It isn't a great and unique gift, being moderately witty, so I imagine dozens of people say similar things on their twitter account, blog, facebook etc.
It doesn't mean we copied someone else, it just means someone else thought the same thing you did at the same time, because it was a rather obvious thing to type.
Now, when it starts to get more elaborate and complicated is when it becomes a bit more dubious. Lots of people may think the same things you do, but do they write the same paragraphs that you do?