I do not know how correct wiki is but L337sP34k was pretty much invented around with Everquest and the original Counter-strike. Probably more so with the latter though. I can guarantee though that me and 5 other friends coined the term pwn about ten years ago at the start of Everquest.

Pwn = own obvisouly, but say you are playing a fast-pace game and typing isn't always perfect. The o is right next to the P on the keyboard. So thus the p became the new O. Don't ask me why we couldn't hit the o but we could hit the w and n keys lol. Noone knew what we were saying though when we first started using it and now its used everywhere. My license tag says WTFPWND, and atleast once a day I have someone who asks what it means. I've recently just started saying "You either know what it means or don't", because if i say "Its something in computer talk" they're like "Ok, nerd." But whatever lol

 

uhh.. pwn was coined in the 80s.. leet speak was certainly around before everquest and CS. You give yourself too much credit.