Does Shocker' ability (from ASM) to put a token on a hit enemy act like Incapacitate? i.e., does it deal one penetrating damage if the hit character already has two tokens? Or does it do nothing, since the power does not say "Incapacitate"?

No, it doesn't do anything extra if the opponent already has two tokens.

Ah, thanks. A friend was using his shocker not to deal penetrating, but unavoidable damage. This clears that up.