As sweetdweb alluded to, just listen to the drum fill near the end of "In the Air Tonight," by Phil Collins, and you will know what a gated reverb sounds like. It is really two processors, a reverb, and then a gate. Reverb will have all the normal parameters; pre-delay, time, diffusion, density, high and low pass filters, etc. The Gate will have all the normal parameters for a gate; attack, decay, threshold, ratio (if it is an expander/gate), etc. I like to send to the reverb, with the gate after the reverb, and I key the gate off of the original signal, and not off of the reverb itself.
Light
"Cowards can never be moral."
M.K. Gandhi