Pwned is simply slang for owned
. See the example for usage.
Pwned is a word that cannot be pinpointed to be originating in anyplace. There is no proof that it came from WarCraft, or Quake, or whatever. I believe it was misspelled by an IRC n00b
, and later, people imitated him. Less informed people saw these experienced people using this, and they started too as well.