Stacking

[Imrahil]

I've been noticing a lot of decks recently that use stacking strategies to set up minion sides (LttG corruption with Preparations and other such things).  I have always been under the impression that stacked cards must be faceup, so that your opponent knows your not cheating and stacking, say, Goblin Runner on The Shards of Narsil.

Is there a ruling on this?

Thanks.

[Tbiesty]

From the rulebook:

Stacked cards are placed face up and may be looked at by any player at any time.

[Imrahil]

Thank you.