I notice that the design for the main comic pages (ex: http://xkcd.com/869/) have changed. Two points I notice:
1. The example comics at the bottom of every page no longer has working links.
2. The menu in the top-left (with Archive, Forums, Blag, Store, About) looks a bit odd, with everything top-aligned. I'm not sure how it was displayed before, but it looked better IMHO.
In case it matters, my reference browsers are Safari 5.1.3 and Chrome 18 on OS X 10.7.3.