As much as I hate to say it, after spending a few weeks now running heroics as a healer on my druid, shaman and paladin after patch 4.0.1, my paladin may be replacing my druid as my favorite 5-man healer. I know all of you shammies out there are going to quickly tell me that I'm out of my mind - so I'm going to caveat this by saying that my shaman is currently grossly undergeared compared to my other two healers. If his gear was comparable, I might have a completely different feeling.
So it took a little while to get used to the new paladin healing mechanics, but I must say, the more I'm using it, the more I enjoy it now. Pre-patch, I used to Beacon the tank, keep Sacred Shield up on him and then just spam flash of light on the rest of the party. Dropping in the occasional Holy Light if damage got intense. I used Holy Shock very rarely, mostly when there was a lot of party-wide damage and I needed a quick "oh crap" heal.
Now, my approach is completely different. I'm trying to quickly judge which of the dps is not going to figure out not to stand in fire / black puddles, purple goop or whatever and I'm putting the beacon on them. I'm using Holy Shock whenever it is off cooldown to build up Holy Power and am then using Word of Glory on whoever needs it the most at that point (not always the tank). I'm only hitting Holy Light now whenever Infusion of Light procs after a Holy Shock crit. Beyond that, I'm using Flash of Light whenever the damage gets a bit heavy - it's a heavy mana drain, so that probably won't be the best approach later on, but for now, mana isn't even remotely an issue, so it works fine.
For the druid, for some reason I'm finding that none of my heals are hitting quite as hard as they did before. My rejuv ticks have lost just a little something and Nourish isn't the monster it once was. Lifebloom has become a beast though, so I'm using that on the tank a lot more aggressively. Regrowth is also more of an instant heal with a tiny HoT, so I'm using that in place of Nourish a lot if someone is getting low. Wild Growth seems to have gotten a lot more powerful, so I'm trying to use that a lot more, even in a 5 man setting. Oh, and I use Efflorescence a lot, just because it confuses people! My overall complaint with the druid is that I am still a beast at keeping an entire raid up, but the druid seems to have lost something in terms of being able to heal up big damage spikes.
I think my plan for when Cataclysm drops is to leave the warlock on the shelf for a bit and level these three healers first. I'm really anxious to try all of these out in Catalcysm dungeons, so I think they'll be my first ones out of the gate.