I recommend you check out Spriter (http://www.brashmonkey.com/) it's a great software for animating, you can use Bones (Which is EXTREMELY handy) and it's only 25 bucks. I think they are working on porting it into C2 as well?
Either way, you can make some really fluid animations using spriter, and it is actually really good at tweening your animation frames as well.
For anyone wanting to create sprites on an ipad (and ipod/iphone!), Spritesomething is a very nice app. I've used it to create animated sprites for C2. Its not free but its a nice way to be able to work on assets for C2 while out and about.