I have noticed some interesting behavior in Cash recently. For one thing he has become aware of his shadow. I mean he's been aware of his shadow for a while but I just noticed him manipulating it in the last few days. Looking at his shadow on the wall he moves his hands and touches his ear. He entertains himself with rudimentary shadow puppets.
More interesting has been his recognition of the teapot. Favorite among his pictures recently sent from home is that of his white teapot (apologies to all the people in that book). For reasons of his own, Cash has always been fond of teapots and enjoyed playing with them. Yesterday Cash pointed at the photograph of the teapot and then pointed to the actual teapot in our room. What's extraordinary about this is that he realizes the photo is representational of the real object. Furthermore, even as dissimilar in appearance as the two are, he knows the concept is the same.
Finally, I think he is playing with his tongue more. Poking it out, touching it, even sticking it out on command sometimes. I don't know that there are more corresponding vocalizations, but it is a good sign.