Last week's AIGA London event on The Aesthetics of Code was excellent. Copious (paper) notes were taken.
Processing particularly grabbed me. It's an environment (a small API and a custom IDE) made especially for sketching interactive and generative art (so the programs are extremely short and it's fairly easy to understand what's going on). The pieces produced with it are pretty, but much more impressive is the work put into the social aspects: the reference material is slim and accessible; there are copious examples for learning. Oh and: when you export the applet, it encourages the View Source mentality. Nice touch. (I've put my first Processing piece [Java] online. It's quite lame.)