Read more at GameSpot

Over time, even gold becomes worthless. For proof, look no further than the hyperinflated economies of World of Warcarft and the Diablo series. From his prior experience working with Blizzard Entertainment, Stone Librande, lead designer on SimCity, has witnessed how rewarding players with a currency, and then building a player economy from that same currency, can have detrimental results.
Armed with this perspective, Librande and his team have set out to create a virtual marketplace that will be economically stable after years of use, while remaining potent enough to influence how you play.