It's a sort of cryptogram or substitution cypher, though a very sloppy and approximate one; 1 replaces L, 3 E, 7 T, @ A, \/\/ W, /\/ N, etcetera.
Edit: Having just realized another possible meaning in your question, 'elite' or '1337 5P33K' is merely a way for people, mostly gamers, to claim superiority over one another, though in many circles '1337' has now become a sign of inexperience.