There's another thread with a similar topic right now. I play both a DPS and Tank. I have a healer, but he's my Alt's Alt.
Right now here's what needs to change:
1. Tanks need to slow down, watch the healers mana, and create reasonable pulls. This has largely occurred in the 4+ weeks since the new spec/nerf/whatever you want to call it to our Threat. You rarely find tanks blindly charging into a room now-a-days.
2. Healers need to work on efficiency. This is largely an internal struggle to over come bad lessons taught by some of the 'free-mana' days of wrath. This has begun to occur, but healers seem slighly behind the curve of most of the tanks I've seen. (Meaning more tanks have learned the hard lessons quicker...)
3. DPS need to focus on what they are doing, follow kill orders, prioritize CC (If that's their role), and avoid stressing the healers. Of all the roles, this is the most 'public' of the struggles to adjust to Cata. Tanks that make stupid pulls quickly take a dirt nap and everyone learns. Healers that are going OOM stupid early either quit healing or quickly realize they can't spam certain spells. But right now it seems like the DPS are the ones in the public limelight. It's the mage who is not using Sheep. It's the Rogue who fails to Sap. It's the Melee who stand in front of the Thrashers (Or whatever they're called in Stone Core) When that big giant is casting quake - Jump. Do you see the tank/healer doing it?