While this strikes me as about about 10 months too late, these sound like some promising improvements to the co-op experience...
Developer Journal: Multiplayer Improvementshttp://us.battle.net/d3/en/blog/9382478/
From day one, it’s been our goal to make Diablo III a great co-op experience, but right now it's not living up to its full potential. Even if you enjoy playing with your friends, it can often feel easier and more efficient to play solo.
Playing solo has a number of advantages. For instance, you can choose your own route. If you're farming for something in particular (like a specific recipe), you can do it as many times as you want. And you can pause the game and attend to things in real life without making anyone wait.
Of course, multiplayer is awesome, too, and comes with its own benefits. For example, leveling up characters with a group of friends can be an amazing experience. Working together with other players to take down bosses or destroy Elite packs super quickly makes for great farming runs. There's resurrections and the banner system, and don't forget farming for Infernal Machine keys and organs. But, there are also disadvantages, like having to coordinate where you're walking and what you're attacking, losing your followers, and trying to find groups that have similar goals to yours without a defined matchmaking system in place.
The point is that multiplayer can be lot of fun, but given the downsides it can often feel not worth the effort. By making it easier for players to find one another, improving social features, and providing direct buffs to co-op groups, we hope to change that perspective.
The stuff includes matchmaking "tags," multiplayer bonuses, reducing MP monster "extra health" from 70% to 50%, Identify All feature at vendors, combat alerts on map (when one party member encounters elite swarm etc.) and player portal/teleportation banners, private chat with up to 99 bnet friends.
This is going onto the test server first.
My only issue with the tags (via a drop down menu, they're still experimenting with different tag names, like Questing, Key Warden, PVP, etc.) is... people lie.
If D3 could sort of determine what kind of player you are simply by how you've played the game over X period of time, that might be neat. Perhaps impossible, but given how intricate achievements are in games today, maybe not...