In a recent blogpost, Norman copied the comic from this webpage and said that he liked it. Well, I rather like that particular comic myself. However, it would appear that he is violating the terms of the Creative Commons license by which you may reprint it. The conditions are simple: Your use must be non-commercial (I think he actually meets this condition.) You must attribute the work to the author (his name is Randall Munroe, but a link to his website would have worked -- Norman failed to attribute.) You must identify the license terms (he apparently couldn't be bothered.)
Oh, by the way, this is also a good comic by the same person. I wonder what the chances that he will risk letting his readers see that one.