a common typo of owned that is used in the same way, or more sarcasticly to mock 1337 speak. If you think pwned can be attributed to a single source you are retarded.
retard1: pwned originated with quake
retard2 no it started with warcraft
nonretard: Its a fucking typo, like 'teh'or 'pron'. I you were older than 11 you'd know typos happened even before 1337 made tham 'cool'.
otherguy:you faggots just got pwned!