If you are an intern, a recent grad, a junior copywriter, a second year law associate, or similar, please just go to your boss and tell him what you intend to do. Your job hunt need not be a secret. Upon hearing your plans your boss will likely be impressed by your ambition and your professional courtesy. Please understand that almost all underlings are terrifically replaceable. Don't be confused about this. If they can replace NASA shuttle pilots, Yankees outfielders, and Price Is Right hosts then they can replace you. What is it you do again? Making a big deal about leaving makes you look silly.