It turns out it has been updating hourly. It is on panel 2946 as of this posting.
You can view it xkcd 1190 here, in animated form, with the spacebar to play/pause and arrow keys to advance or rewind one panel at a time so you can read the word balloons.
I think what really amazes me is how inaccessible this is from xkcd's own site -- buried in the archive, with no archive of it's own, posted in a form that more-or-less guaranteed no viewer would see even half of it.
It's interesting in its own right, though.