Starting right this moment, and up until April 22 at 10AM Pacific, Xbox Live Gold will be free to everyone within the US, Canada, Latin America, and Japan. This means anyone within these regions that don't pay for Xbox Live will be able to play online multiplayer, and access apps that are usually put behind the Gold membership only wall.
As part of this free Gold weekend, Black Ops II, Assassins' Creed III, and Far Cry 3 will be offering up double XP to all players. Plus there's this special SHiFT Golden Key made for Borderlands 2players on the Xbox 360: KTW3T-ZXXS5-JBSJF-5FJT3-6TB9X.
Free Xbox LIVE Gold Weekend for US, Canada Latin America and Japan [Major Nelson]