- Priest on pally = win
Druid/shammy on pally = just ducky
pally on pally = sucktastic
This is in terms of SA for the tank.
Shammies can make good single target healers, as they are a healy hybrid like holy priests. Chain heal and their quick cast times make them strong raid healers, but Earth Shield and its bonus to lesser healing wave make them good for a tank heal as well. Water mastery, LHW, and Earth Shield are good major glyphs. Healing Way is a rubbish point expenditure because it is rare that a shaman will spam Healing Wave, and the talent does not benefit LHW, which is teh shaman's primary heal.
Pallies, more or less, are tank healers. Period. Their primary heal is Holy Light, which is a really shitty way to raid heal. Glyph of Holy Light is definitely a must have. Imp Conc Aura has very limited applications in PvE, but where it's useful, it's a godsend.
If you have more specific questions, I can try to answer them, but as far as an overview, that's what I've got for you.
We have basically a Druid healer who has been tasked with assigning healers during raids. The Druid healer did not want to act like they know everything, so they bring it to the community to seek useful advice about what classes are capable of healing, useful spells, must have talents, ect. So the second commenter is the one who responded with the pile of $#!^! Why does it aggrevate me so much? I know what Paladins are capable. Hell, I even know what the other healing classes are capable of. I think the reason why it annoys me is that I have to work my ass off in raids to put out solid heals and have played since early on as a Holy Paladin. I take pride in my class and cannot stand when someone who has no knowledge spews forth such crap.
Okay, I have calmed down. Now let's take a closer look at what answer we could have provided to the original poster. When looking at the four healing classes, we have basically five types of healers (sorry but I know nothing about Disc Priests). When you think of a Paladin, you automatically think of a single target healer and that is a fair assessment; however, to say that we cannot raid heal is really not appropriate. It will depend on the skill of the Paladin and the make up of the group. Ninety percent of the time, we are best suited for being assigned to a tank, but to say that we have only one heal is absolutely absurd. We have three very useful heals. The first is Flash of Light (FoL), which is a standby quick cast heal which provides solid heals and can be quickly spammed to either a tank or to members of the raid. The second heal is Holy Light (HL), which is a large heal that is best suited for single target healing and should be used by a Paladin with a good amount of haste rating (of course as you run the raids this should not be an issue). The third heal that we have is Holy Shock (HS), which is our mobile heal. We do not have an area of effect (AoE) or heal over time (HoT) to use so we have to be constantly aware of line of site (LoS) issues and ranges of our assignments. In addition to our heals we have Beacon of Light (BoL) and Sacred Shield (SS). A skilled Paladin will also utilize the ability to create instant crit FoL, HL, and HS. Another skill that Paladins should learn to use is the combination of Hand of Sacrifice (HoS) followed by Divine Shield (DS). If you are not familiar with that little combination, it is a trick from older Paladin healing days and a must have for those in PVP. The final tool that we have is the use of Judgement of Light (JoL), but that is often better served to be used by a ret Paladin (but that would be a conversation for another post).
So right there we would have provided a solid overvue of our healing abilities to the original poster and not put down any classes in our answer. Now to answer what glyphs and talents are needed is somewhat trickier as these can be augmented by other members of the raid. I personally would prefer a Paladin who went into the ret tree and picked up the free crit rating, as that would have freed them some to look for haste and MP5 gear. (And please do not say that MP5 is not important as mana regeneration is always important and I will never change my stance on that.) When looking at glyphs the one glyph that is important is the Holy Light glyph. So there you go, if you ever see a poster with a question about what we can do or what to look for, present a clear cut answer about YOUR class abilities and leave the putting down of other classes out of it. I truly believe that most classes are viable and that the skill of the player will make up for any lack of ability and perhaps, just maybe, there is still some skill involved in this game.