So, what does the keyboard mean to the gamer? It's only the most crucial part of your gaming set up. The way I look at it, and this should make it simple for you console gamers to understand, the keyboard plays the role of the face buttons in the keyboard-mouse setup. The keyboard serves to move your character in space while the mouse typically controls the camera. In other setups, the keyboard functions as a command center for all your units and for movements on a map.
The best keyboards for the PC gamer have to be those that allow for custom-setups. Beyond that, the essence of buying a keyboard comes down to only two things: Ergonomics and Response Times.
Bluetooth or Radio-enabled keyboards will have a very slight delay in response, and could even turn off as they run on battery - meaning that most gamers who have the room will avoid them, working with wired keyboards instead.
Ergonomics play a huge role as well. Keep in mind that you'll be resting your hands on the bottom part of the keyboard for most of the day, and even while you play, your left hand will always be on the board. This means that for some people, ergonomically designed cushions at the bottom part of the board, or a separate cushion below the keyboard, work best.
Your keyboard, much like your mouse, is an extremely personal choice, and if at all possible, you should try to test one out at a local electronics store (even if you don't end up buying it there). By looking and feeling how the board feels on your fingers and wrists, you'll be able to efficiently pick which one will work best for you. And that's all there is to it - follow my advice and you should be on your way to gaming nirvana in no time - with no Carpal Tunnel Syndrome either.