No, still nothing happens. Or more appropriately, very little happens. However, when they are setup as you describe -- electrodes, solutions of their own salts, salt bridge (or semiporous membrane, or even just layered over each other) and then the electrodes are connected by a conductor, then the reactions proceed. Here's a question for you -- why is this so? What's happening, and how can you explain the similarity between a functioning electrochemical cell, and the reaction between dissimilar metals?