It looks like EA is taking a play from Call of Duty and Gears of War by having special weekend promotions for the multiplayer aspect of their game. This weekend you an hop on Mass Effect 3's co-op gameplay with a chance to earn special item packs just by completing the following challenges.
Operation Goliath
Any player who is part of a squad that beats the Reaper faction on Silver difficulty or better will unlock one Commendation Pack. This means that at least one member of the squad must be extracted at the end of the mission – this will earn all squad members the reward. Each player can earn a maximum of one pack and each pack contains a random N7 Arsenal Weapon. Originally only available as single-player weapons via the N7 Collector’s Edition, these multiplayer variants will be exceptionally rare and are NOT obtainable through regular purchasable Reinforcement Packs. The Commendation Packs will contain one of the following guns at random: (1) N7 Crusader Shotgun, (2) N7 Eagle Pistol, (3) N7 Hurricane SMG and (4) N7 Valiant Sniper Rifle. Destroy as many brutes as possible – if the multiplayer community kills a combined 1 MILLION brutes within the hours of the challenge, ALL players will receive a Victory Pack as a reward.So we have both a squad level challenge and a community level challenge at stake. Co-Op on multiple levels. The challenge runs from 3/15/2012 at 5PM PST to 3/19/2012 at 5AM PST. The rewards will unlock on Tuesday, 3/20/2012.
To participate, all players must enable the data tracking option in the game (options-> online-> upload gameplay feedback-> make sure it’s "ON"). This is only available on the Xbox 360 and PC.
Here are some strategy videos released by EA and Bioware on the co-op.