In a word: walking.
Note the upraised arms; this is obviously because we held his hands as he learned, but along with the smiles and laughs of delight, always remind me of the arms-up-yay emoticon: \o/ !
Also, SteelyKid has discovered the joys of hunt-and-peck typing on the keyboard (also knows the functions of the caps lock, delete, enter, and space bar keys, though she has an idiosyncratic approach to white space) and has started emailing her friends via their parents. Seriously. I wonder how soon she can learn touch-typing . . .