In a sort of competitive co-op spirit, Red Dead Redemption has a challenge for you. The challenge is simple: collect XP through any of the multiplayer modes available in the game. The goal here is not only to boost your own XP in the game, but to accumulate XP as a console. So the Xbox 360 and PS3 will tally all of the XP earned by players to see which console is truly superior in the Rockstar Wild West.
Boot up your platform of choice and jump into any Red Dead Redemption multiplayer session. From Free Roam to Grab the Bag - whatever your pleasure. Enjoy your multiplayer game as you normally would and when your session ends, all of the XP that you accumulate will be automatically added to your platform's XP grand total.
Track the stats of your console and just have fun playing a game we already adore. By participating you’ll unlock avatar awards and make your console of choice look good, not to mention you’ll get to play co-op with some quality folks. Unless of course you choose versus, in which case we can’t help you.
Source: Socialclub.rockstargames.com