I have wanted to write something about raid healing as a paladin for some time. It seems I'm late, several guides have been published around and I invite you to read them if you're interested into healing (esp. as a paladin obviously).
Holy Paladin FAQ - v1.0 (Pre-3.1) on Banana Shoulders
Holy Paladins as Raid Healers on HoloyPaladin.net
Two Approaches to Gearing Holy on Pallymar's Take
I advise you to read more on these sites, if you haven't already. They are full of very good information for Holy Paladins.
I'll probably try to write something on my own some time (soon ? who knows).