So, you've decided to jump into Cataclysm healing with bubbles, or you're tired of getting trounced on the meters. Either way, welcome to the bubbling side, we have Power Infusion but sadly, no cookies.
First off, disc healing is no longer about spamming PW:S. You do not have the mana pool to support it, trust me. So, here's your spells and when you might wish to use them. Keep in mind that there is no healing rotation, and this is just one way to heal. Also, I'm raid healing, so I talk about spells more from that perspective.
Power Word: Shield-> still important, still useful, but now costs more. In raids I try to keep this up on the tanks, and throw it on dpsers or healers in immediate danger. Try to avoid having shields fall off, you really do want damage to break them for the mana return.
Flash Heal-> Honestly, the only time I use this spell any more is when I hit it by accident. It's expensive, and if I need a fast heal, I have other spells.
Penance->Your fast heal. Also the "crap, about to die" heal and the "yay I can stagger the tank" heal.
Greater Heal-> best used with the borrowed time buff from a pw:s cast. When I need a heal and penance is on cooldown, this is my go-to.
Prayer of Mending-> Keep this Frisbee of healing goodness bouncing. It's cheap and a smart heal.
Prayer of Healing->This is your group heal. It's best used with Inner Focus, and remember it's a group heal, not a raid heal. You need to cast it on someone in the group you want to heal.
Renew->useful as an extra tank cushion or a on-the-move heal for someone who needs to be topped off but isn't going to die immediately
Power Infusion->If you're down to the wire on an enrage, throw on a dps (mage preferably). Otherwise, keep it for yourself for a little extra healing oomph
Pain Suppression-> Your tank-saving cooldown. You could possibly also use it to mess with your tanks, but I wouldn't recommend it.
Leap of Faith-> a way to pull people out of bad stuff, or a way to mess with fellow raiders. You can also use it to help kiters.
Inner Focus->Try to use before as many prayer of healing casts as possible if you're raid-healing
Power Word: Barrier-> great for incoming heavy raid damage, just keep in mind the long cooldown and that people have to stand in it
Inner Fire vs Inner Will->Inner Fire's best used for tank healing, where you need more power to your heals. Inner Will's great for raid healing, as it lets you throw more shields about without going oom and yay faster movement.
Now to the specs and glyphs. Disc priests have a choice to make, spec into Archangel and smite-healing, or not. Archangel does not return enough mana to make up for the mana you used smiting, and you don't have control over who gets healed with the smite. It automatically heals the lowest target within 15 yards, including temporary targets and pets. I'm currently spec'd into archangel, but I'm going to redo that, as I'm really not using it. I like the idea, and I'd say try it both ways, and see which works better for you.
Disc spec without smite and archangel
Disc spec with Archangel
There's some optional points in there, especially in the shadow tree. Personally I'd pick up the spell haste, but that's optional.
Primes: Penance, PW:Barrier, PW: Shield, and/or Prayer of Healing
Majors: Divine Accuracy (for smite builds), Prayer of Mending, and whatever else you'd like to take
Minors: Shadowfiend, Levitate, and whichever other one sounds appealing
Next up, updating the gearing post!