Amazon.com has a unique pre-order bonus for Uncharted 2: Among Thieves. It looks as though Uncharted 2 will have the familiar treasure system, if you pre-order from Amazon you will have a leg up on the competition.

They are offering a “Treasure Map” that indicates all the hidden locations of the treasures within the game. The map can be viewed on both your PS3 or PSP, so expect this to be some kind of a digital download.
Pre-order “Uncharted 2: Among Thieves” and get an Amazon exclusive treasure map. This bonus video strategy reveals the secret locations of treasures hidden within the game and can be viewed on both the PS3 and PSP systems. Access codes will be sent within 10 days after the game releases. Offer good while supplies last. Must be sold and shipped by Amazon.com to be eligible.
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That's pretty... lame. I mean, the treasure locations will be all over the internet soon enough after the game releases...