Contrast that with two old xkcd comics: #12 and #62. In these comics, you really have to know what they are talking about to get the joke, and it's not obvious at all from the comic what a poisson distribution or karnaugh map is. It's a joke made for people who already know these things. That's the kind of thing we don't see anymore - the requirements, so to speak, of the comic have been lowered substantially.
The question, then, is whether that is a problem. I don't think it's a problem per se but it is indicative of the selling out of xkcd - the shift from actually wanting to make actual nerd jokes (and not "nerd as a subculture like any other" jokes) to wanting to have as broad an appeal (and as broad an audience of potential shirt buyers) as possible. What do you guys think?
Lastly, while randall's graphical depiction of the conjecture is nice, I find myself fascinated by the patterns in this one.