As it did with Resistance 3, Sony plans to impose its "PSN Pass" on Uncharted 3, meaning multiplayer access to that game will be subject to a one-use code included with all retail copies. That's per Juan Jimenéz, Sony's software manager for Spain.
That means that used copies of Uncharted 3 aren't assured of including multiplayer access and, if their code is missing or has been used, it'll cost $10 for someone to activate it the features
Online pass schemes, earlier implemented by Electronic Arts, THQ and others, are an indirect way for a publisher to get a cut of used sales, but they're more intended to incentivize buying new.
Interview with Juan Jimenez, Software Manager of Sony Spain [The Vault (Spanish) via Joystiq.]