Answering a question in their latest weekly update, Frankie, of Bungie.net, confirms that the Double Team playlist (2 vs. 2) will be appearing sometime next week. There has been speculation as to whether or not Bungie will make a new map available, seeing as the current three maps are believed to be too large to handle only four people. The quote is as follows:
"Burn01: Is double team going to be on the beta?
A: Wait, I'm not sure what you're saying. You're trying to claim that Double Team might go into the Beta next week? Wow. That would be awesome."
Full update after the link.