The weblog Drawn! points to a 37 Signals discussion of Scott McCloud's Understanding Comics.

I read Understanding Comics several years ago, on the advice of a videogame designer. I was a little skeptical, but McCloud's analysis of how comics work is remarkably insightful about communication in general: not just in how things are created, but how to design things that people can engage with. We're using the text in my Narrative for New Media course this semester; we're just starting, so I'm not sure how it will go, but the students said it looked interesting.