Since the date on the last writeup, the popularity of xkcd has become even more ubiquitous. xkcd seems to have replaced The Onion as the common ground for geek discussion. The words "oh, this is just like the one xkcd strip..." are now a conversational touchstone. How did xkcd so quickly insinuate itself into our consciousness?
One of the things barely mentioned in the above writeup is the actual art on the strip. The art is, to say the least, minimalistic. The most typical strip or panel involves stick figures, without faces, talking with each other. Some strips or panels are even more bare, featuring a simple chart or graph. Is the success of Randall Munroe simple luck, then? Or even worse, is he simply deluding hordes of geeks by giving them the Linux references they want, without actually having any talent?
I think that that is not the case. Although it may be an example of judging things in hindsight, I think that the stick figures used in the strip do manage to convey a lot of emotion and meaning in fairly simple motions and postures. When Scott Adams' Dilbert strip became popular, it was also the simplest drawn strip on the comic page, but also managed to communicate to people about familiar situations. Going further back, Charles Schultz's Peanuts strip was also fairly simple artistically, but managed to gain people's sympathy using just the lines around Charlie Brown's eyes. I think this is part of what makes the strip's art meaningful and popular---there are some very emotive stick figures. The other aspect of the strip's art is that some of the strips show a lot of artistic creativity and skill. Occasionally, the characters move around in dramatic, surrealistic landscapes, and some of the tricks and visual jokes, such as strips dealing with recursion and dream sequences, are quite sophisticated. Two recent strips focusing on logarithmic pictures of the universe I found especially artistically and scientifically well done.
For all of those reasons, I believe that xkcd is well done, and has some staying power, and is not just about using or abusing geek cred.