Actually you could do this in the closed beta as well, all you need to do is invite someone from the oposing faction to your group and then que as a group. Sometimes it doesn't work but more often than not you'll both end up on the same side regardless of the fact that one of you doesn't belong.
This bug has been in since before the patch, and I submitted a bug report the first time it happened, though I should probably send another one for the second incident.
The first time, I'm not 100% sure what happened. A Klingon player raced past me with cloak + full impulse, got shot by myself + other Federation players, and flew right through some guy's mines. He seemed to be lagging a little bit, and within a few seconds he was showing as friendly to all of us, and hostile to the Klingons. I couldn't attack him, but could heal; and he and other Klingons attacked each other several times. He even showed up on the Federation side of the scoreboard. I tried inviting him to a team, but it gave an error saying he was on the wrong faction.
The second incident it actually happened to me. My crappy/unstable DSL totally cut out during a match, but came back up within a few seconds. When I logged back in I was still in a group with the one friendly player that I'd been with before, and was able to see that they were engaged in combat across the map. I raced over to them at full impulse, and when I got close enough I saw what appeared to be a Vulcan player name who showed as friendly to me; I targeted that player and noticed low shield/hull health, and dropped some heals as soon as I was within range...at which point I noticed it was one of two Klingon ships that were engaged in battle with my Federation friend.
All 3 ships showed as friendly to me at that time, and I could take no hostile action. The Klingons, however, did begin shooting at me (after I'd healed one - the nerve!) After a few minutes, I got dropped from the group I was in, and all Federation ships turned hostile (though Klingons were no longer able to shoot at me). I checked the scoreboard, and sure enough, I showed up on the Klingon side.