We have the same problem over here. I too just reviewed the BWSAYP and saw the same thing. I had just been ignoring my DS when he did that, but not really taking him out of his high chair as soon as he starts. I am going to start doing that. And I think that even though I've thought I haven't been giving him a reaction, I think I have, so I need to work on that. It's very frustrating, especially when they don't have any words (mine doesn't).
Lemonthyme - I feel your pain! DH is so embarrassed by me because I'm always picking up food that he throws in restaurants, but I feel so bad -- it's not the waiter's fault!