I was the Character Setup Lead for the show, running a team of four body riggers, with Jarred Love as the face rigging lead.  Aside from running down a million little technical issues that crop up and keeping my team busy on the right stuff, I sculpted the muscle and fat shapes for the characters as well as all pants wrinkles.  Keeping their fat little torso in the proper proportion as they moved around while still showing some musculature was a challenge, but I think it turned out really well.  The pants wrinkles worked really well too, and we didn't have to do any cloth simulation except for a few special cases where they got wet or high wind was present. I also found some time to develop a plugin that would make the skin squish naturally when pressed.  Their big heads were often in the way when the animators move their arms around, so having an automatic squishy face saved a lot of their time while also making the smurfs more believable.  Mike Stieber also worked Squishy into the feet so the feet had a pillowy feel that helped to plant them in the real world.

Release Date: July 29, 2011 Visual effects and animation by Sony Pictures Imageworks.

Imageworks released a short video showing how we build a scene - from modeling the character, to rigging it (that's my part), then animating, texturing and lighting it.  Unfortunately I wasn't able to really put a lot into the video about how we rig a character, but this gives a nice overview.  

Three apples high’ – Imageworks builds the Smurfs from Prashant on Vimeo.