Nodebox is a programming and visualisation tool using Python. Like Processing it allows you to product animations, still, interactives as well as exporting to Illustrator SVG files and PDF. It is for Mac OS X only and leverages Core Image.
I’m sure someone mentioned this to me ages ago and I’ve just forgotten about it. It looks quite promising, though very similar to Processing albeit it somewhat simpler at present. The good thing about it, for me, is that I’ve always felt Python was pretty close to Director’s Lingo, which was the first scripting environment I properly learned (not including some BASIC on the ZXSpectrum and BBC Micro).
Like Processing, Nodebox is free and open-source and has a bunch of libraries for it (including one for the Wiimote, which should make physical interaction prototypes fairly easy to knock together) and sounds like it might be useful for teaching interaction design projects though.
If anyone has used it, let me know how and on what. I’m interested to see where it might be put to use.