Starting on October 1st, everyone in the U.S who buys a foot long sub, a 30 oz. drink, or a bag of harvest cheddar flavored chips from subway will automatically win free access to Uncharted 3's multiplayer. The servers for the multiplayer will run from October 1st through the 31st, and all progress you make during this time will carry over into the final game. One code can give you the early access, but additional codes can win you an Uncharted 3 dynamic theme, a custom multiplayer weapon, a Nathan Drake multiplayer skin, a multiplayer cash bonus, and a Playstation Home avatar. Each code will win you one of these prizes, as well as a chance to go on a trip. (The Subway site is very vague about what the trip is) You can only enter three codes per day, which means that you will have to go to subway at least twice if you want everything. It may be shameless advertising, but it's working.
Check in within the next few days to get my Uncharted 3 Multiplayer First Impressions, or go to Subway, buy a sandwich, and play it yourself.