Filth you're a young'un then, it's been around for a longer time than that... It generally gets started by the AOL script kiddy wannabe crowd (or the equivelant thereof) and spelling it that way indicates you are at LEAST 25 IQ points below the norm and/or are 8 years old and think talking "leet speak" is cool.
The ONLY person that should ever be allowed to use leet speak is Pyro on megatokyo, but only him because he's mentally insane.