You'll Need A PSN Pass For Uncharted 3's Multiplayer
Uncharted 3's multiplayer is a well-designed part of the package, and Sony knows it. As if to reinforce the point, players won't be able to check out that online component unless they first redeem a code for a PSN Pass. As with other games that have online passes of one form or another, that code is bundled in new copies of the game.
If you don't buy the game new, and your copy of the game either doesn't include the code or it's already been redeemed, all is not lost. You'll just have to pay $10 to play online.
Are you used to this concept by now, or does it still bug you?