Damnit Mike Mearls, now you've got me thinking about Turn Undead, a mechanic that I usually ignore!
Okay, Turning Undead is handled differently by every edition of D&D, so let's break it down.
4th edition - It's a Channel Divinity power, once per encounter, hits all the Undead with damage and shoves them away(or maybe they ran away? 4th edition doesn't care about flavor, or maybe the DM/player is supposed to supply it.)
3rd edition - It can be used multiple times per day(based on Charisma), Undead run away or are destroyed, and will come back shortly. Roll once on a byzantine table and add level, then roll 2d6 and add charisma(I could be misremembering this because there were feats to modify it.) for number of HD affected.
OD&D/Basic D&D/AD&D 1 & 2 - It can be used unlimited times per day. Against intelligent undead, the cleric is locked down holding up his symbol and roleplaying the act of Turning. When the cleric ceases to hold the effect, the intelligent undead stop being turned(unless they were destroyed, of course.) Against unintelligent undead, they are turned for an ambiguous amount of time that might be permanent. Roll on a byzantine table, then roll 2d6 to see how many undead are affected.
FIRST QUEST AUDIO CD GAME - It can be used once per hour, and the Turn effect lasts for one hour. Roll on a byzantine table to see which undead in the encounter are affected, but all results happen to all the undead in the encounter.(Turn/Destroyed/Nothing)
I think I might favor the last one, because it's so SIMPLE. The ability to affect an entire encounter is offset by the fact that it's only useable once per hour, so you probably won't be using it on very many encounters during a standard dungeon crawl. Undead encountered during travel are likely to be made a nonentity, but that seems like a desirable result of having a cleric in the party. Undead encountered while resting might require that the cleric maintain a vigil the entire night to keep them from coming back, which could lead to some interesting RP!
I'm posting this here for discussion, however. I'm especially curious what my players who play Clerics think!