Some people may have noticed that turn undead, as of recently, has been scripted to show surrounding PCs the holy symbol of the turner's god, subject to identification upon successful lore rolls by individual observers (Also scripted. The DC depends primarily on the deity in question, and other factors). This shouldn't affect most clerics, who should be vocal about their worship. For the more secretive, however, you may want to watch out for this system.

If you receive this message as an observer to a turning:

As he turns undead, (cleric/paladin) presents the holy symbol of (deity): (symbol description)

This means that you have successfully identified a holy symbol, and you know which deity the Cleric or Paladin serves.

If you receive this message:

As he turns undead, (cleric/paladin) presents an unknown holy symbol: (symbol)

You do not know which deity the holy symbol belongs to. You do not know which deity the cleric or paladin serves unless you are told. There are no exceptions, except in circumstances where a DM has been contacted, due to some extraordinary background or events in-game which leave no doubt that a character would be able to identify a particular holy symbol.

Don't metagame. It's not cool :(