Well, browsing with NoScript, I wasn't even aware of this gag until I returned to read HN comments some 20 hours later (as it looks, the Comic Sans is firstly set via JavaScript, along with the subsequent flip back to the 'normal' serif.)
Maybe I'm reading too much into it, but even if just an unintentional byproduct - isn't that a nice "additional" reward for people that don't allow running unnecessary scripts on random web sites?
I see that the font changes to serif, when the text is scrolled. Is that funny? How does this HTML work?