I see these as an evolution of the encounter trap from Dungeonscape. For those people who haven't read it, the Encounter Trap is a way to get the entire party involved in a trap encounter instead of just the rogue. There was a comment about traps from one of the designers saying that the new mechanics for them "won't be a surprise for those keeping up to date with the evolution of traps in the game."
So, I think that social encounters will be modeled after encounter traps.
Basically, the way encounter traps work is that they list all the methods of bypassing EACH part of a trap and then list the initiative modifier and duration of the trap.
So, you might have a trap where the first person to stand on a certain square causes spears to come out of the floor in every space in the room for 5 rounds. Each round anyone in the room gets attacked with 2 spears, and they show the attack and damage rolls of the spears. It will then list the DC to disable the WHOLE trap at the trigger plate itself before the trap goes off. It will list the AC and the hardness and hit points of EACH spear if anyone wants to destroy the ones in their square and prevent damage for the next couple of rounds. It will show the disable device roll on EACH spear to disable it.
This enabled each member of party to deal with the trap in their own way. The wizard could fireball the trap and take out all the spears causing no more damage in further rounds, the fighter could sunder them and stay where he was safe from more damage. The rogue could disable the ones in his own square, etc.
So, I believe this will be translated into an "encounter" that will enable each member of the party to help a social situation in their own way. For instance it might list the "point" value one gets for succeeding on a DC 10, 20, or 30 intimidate check and a similar value for Bluff checks and similar value for Diplomacy. Then you add all the points together and you see if it beat the DC. If it does, the party defeats the social encounter.
It would be a fun idea for all the party members to work together and I've seen some hints that they might go this route.