I know that software that's not 'free' (in either sense) is kinda contrary to the spirit of Linux, but at the same time, I'm glad to see companies finally taking Linux seriously enough to produce Linux versions of their products.
For anyone who doesn't mind the 'non-free' aspect, there's now a really nice animation program for Linux, from e-frontier. I've been playing with the demo for about a week now, and it seems to be a nicely thought-out and feature-rich piece of software.
http://www.e-frontier.com/go/news
Now if only they would do the same with their 'Poser' program, I could really get rid of XP on my last remaining windows machine.