I will never get a wireless mouse and/or keyboard for gaming. Given my luck, the batteries would fail right when I'd have the chance for the best kill in the game.
However, wireless is very good for casual use, when timing isn't necessary and if a battery fails, it's no big deal to go replace it.
My girlfriend Nikkie has wireless both (Logitech), and it's really fun to just sit on her bed and type and chat with friends online while surfing.
However, I need to go to my laptop and its 2 year old opitcal corded mouse (touchpads can burn) when I want to play. I'm too paranoid to use the wireless mouse and keyboard when I care about the integrity of my Soviet base or my rushing Marines (I'm an avid Red Alert 2, Civilization III, StarCraft fan).
And yes, yell at me for having a laptop and wanting to game on it. I don't care. It may have been more expensive than a desktop of the same features, but the ability to just up and move it with no effort is key to me in a college setting. I wouldn't want to try the same with a desktop.