This just occured to me.
Healing in the past has been about finding a good balance between putting out as much healing as possible while keeping mana cost low (cancel casting and downranking, anyone?).
Healing in WotLK is largely about HPS - if you don't heal constantly, people die in most raid encounters. No one ever runs out of mana anyway, and that's what we've got cooldowns for.
Now I'm quite prone to looking at the meters far too much lately, and I've been thinking about where that will leave me in times to come. In Cataclysm, we're supposedly going to worry about mana cost again and trying to keep overhealing to a minimum.
This will mean that the meters aren't as important anymore or at the very least have to be used in a different way. I mean, now it's quite easy to see when a healer fails because they're just not putting out a lot of heals. In the future, that will surely still be a factor but overheal-meters will probably be important again, Disc priests might have it even better because we aren't as prone to overhealing, and healers might actually fail again by running out of mana.
I actually wonder if they'll increase the mana cost of PW:S by a lot because Shield spamming is easier than Paladin healing, right?
I'm not sure why I made a thread about this, I guess I just wanted to write it down somewhere, so I'll just leave it here.