If you play close enough to your PS3 a normal USB keyboard for a computer works. I just played for a week or so on a PS3 (I'm normally PC) while I was home with family for Christmas. I played with a PS3 controller adn then for chat purposes I used the USB Keyboard. Now, unfortunately, it can't be a wireless keyboard as the PS3 has no way of downloading the drivers for that, but a wired one works just fine. And if you already have one, then you don't have to spend the extra money on the PS3 controller keyboard.
