World of Matticus has an interesting piece up about a touchy subject in raidleading: calling the wipe. It's a tough job leading the raid. Everyone's there to down the boss, yes, but especially when learning a fight, a raidleader has to balance a lot of different priorities-- are potions used or not? Who rezzes after a wipe? How are the healers balanced? And when things go really bad, they have to decide, sometimes on a moment's notice, whether to call a wipe and reset the encounter, or try to push onward. Everyone knows what's possible-- everyone's seen a fight where the last Mage left is able to get one last fireball off and finish off the boss-- but the raidleader has to look at reality and make that call.
Now, Matticus is actually pretty gung-ho about things-- he says not to wipe unless you're down to your last healer and you've only got one rez left. I agree that there are times when soulstones should be popped (if we have enough locks, we'll usually soulstone our main healer, and so if aggro ever gets lost, he pops right back up again), but if you're on the first attempt of the day, there's nothing wrong with saving a few rezzes and repair payments. Especially in a place like Gruul's Lair on High King Maulgar, where it's easy to get out when things go south, there's no reason to fight when two tanks drop on a bad pull. Just run, save the money, and come back when HKM has reset.
But Matticus is dead on about what happens after a wipe is actually called.