I think Rhody Trader gives the best definition. Hedging reduces a form of risk. Given the natural inverse relationship between risk and reward (or at least the academic inverse relationship), one should expect lower mean returns and lower variance of returns from hedging. If your hedge adds extra PNL, then you should really think as to whether or not you're actually mitigating risk.
In the book "Boomberang" by Michael Lewis, among other things, he investigates the causes of the Icelandic financial crises, and he found that prior the the crisis, speculation had become almost a national passtime. He said that people loved to hedge, as long as the hedges made money too.