It's an application aimed at more 'traditional' frame by frame animatiors, lots of tools for improving their efficiency, apparently good for doing up animatics too: http://www.toonboom.com
It's digital sketching and painting, with a workflow designed around animation and asset management. They also have Storyboard Pro for developing animatics/leicas, which is pretty nice.
Flash wasn't really able to handle the heavy textures in this show at HD resolution and so we went with Toon Boom instead. Steep learning curve even for Flash users but it had its advantages!