DS has learned how to shake his head for no. Anytime we ask him a question, like "Can you say mama?" he'll shake his head and smile. He's just starting to get "yes" head nodding figured out as well. I asked him today if he wanted to go outside and he was beginning to nod instead of his usual head shake. I love it! He thinks it's pretty fun too!
It's nice that he's learning "yes" as well. Drew figured out how to shake his head around nine months but I swear it was another two or three months before he started nodding. He was much more interested in "no." :-)
Re: "No" is so much fun!