I've received e-mail resume submissions from people where I swear I was hearing from Prince (hey some of you are my age and know what I'm talking about, right?). As Martha explains, the appropriateness of "Internet-speak" is contextual. This should never happen (but it does):
Plz find my resume attached 4 U 2 review.
I've found myself becoming comfortable with the occasional emoticon, despite my initial dislike of them (too cutesy...though Dave Barry makes them funny here). I really can't get beyond : ) and ; ). They actually help people like me who have been told they are "too direct" in e-mail to soften it up a bit. ; ) Besides, it would sound weird to say "I am winking at you now" at work. I'm just saying.
But when letters or numbers are substituted for perfectly good words? And when the purpose of the communication is to introduce yourself as a job prospect? I wouldn't advise it.