Some issues will be addressed in the patch, others will have to wait for cataclysm.
Binary State Tanks
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What this means for healers is that their heal has to be in place fast. You can't afford for the tank to take a second hit before your heal lands, she must be topped off at all times. So the healers spam their fastest heals on the tank until the boss dies, without giving much thought to it. Many encounter mechanics also require this style of healing for other raid members, most prominent in my mind right now being Anub'Arak 25 men hard mode. A target hit by penetrating cold cannot afford to take a single tick of the debuff without getting healed first, healers therefore have to rely on speed at the cost of anything else. It doesn't matter if a spell is mana efficient or provides higher health per second, if it's not fast it's not good enough.
Patch 3.3 addresses part of this problem through a mechanic called
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This change feels like it will turn tanks into heal sponges, just as a boss is a DPS sponge. Will we see the arcane mage hitting Arcane Blast x3 and then Missile Barrage standing right next to the shaman hitting Riptide, Healing Wave x2, Chain Heal, Healing Wave x2 all fight long? I truly don't know, but if they turn tank healing into just another form of DPS I don't think the change will improve anything. For 3.3 we can expect slightly fewer one-shots of our tanks and might get some more real healing in. I suppose that isn't bad.
Infinite Lyrium
In Dragon Age: Origins mages are quite a bit more powerful than anything else and one of the reasons for that is that mana (lyrium) potions are in virtually unlimited supply. While I wouldn't go so far as to say that casters in WoW are overpowered, we pretty much have an endless supply of mana as well. Between various talents, Replenishment, Blessing of Wisdom, Innervates, and mana potions it is rare to see a healer actually go out of mana in all but the toughest of fights. Having a virtually unlimited supply of mana means that the mana efficiency of your spells doesn't matter anymore and you can simply use the spells with the best effects (or, more likely, the shortest cast time.)
The last time my shaman had mana issues was when we first did Algalon 10 and didn't have Replenishment in the raid. You could say that that is because of all the mana regeneration gear we healers have - but you would be wrong. I'm actually actively trying not to get gear with mana regeneration on it and have even changed my meta gem to a vastly inferior one because that one doesn't deal with mana regeneration. That's how irrelevant mana is. Ghostcrawler made a nice statement on how they plan to fix the mana issue for Cataclysm. Alas that likely means that mana will continue to be unimportant for Icecrown Citadel.
Have a Flask of Pure Mojo ready when you enter Icecrown Citadel just in case, but my money is on a continuation of how healing works right now. Don't vendor those Imperial Manta Steaks just yet, shamans. Haste will still be paramount if I'm not mistaken.
If I'm not making you feel overly positive towards patch 3.3, watch this awesome trailer by Vodka. (Warning, spoilers inside.)
1I'm aware that this is a gross oversimplification of the math involved here. If your tank has 50% avoidance, a 20% dodge reduction means a 40% increase in hits which in return means a 29% reduction in damage per hit to keep it equal. Or so my napkin says.