Right or not, Shockey should know the refs have their eye on him and not do anything to hurt his team.
The penalty is delay of game for spiking a live ball (and so it is different than just spiking after a TD)...yes, lots of players do it and get away with it -- though when it's on a play that goes out of bounds and stops the clock, you won't be a penalty called, but every time it happens in the field of play, I wait for the flag to be thrown. The players should know not to do it, but as we've seen, there are tons of undisciplined players out there.