The throwing itself is not a huge worry to me... unless it's going to break the toy.
The throwing AT someone is my main issue (although it's my 3 YO who does it on the odd occasion).
I'm not sure how to stop it. I think it's something they grow out of. I'm sure it's just another way of them learning how the things in the world work.
Sorry... no real advice. Pointless post really.