"Target will begin selling Facebook's virtual currency as gift cards on September 5, becoming the first brick-and-mortar retailer to do so. Facebook Credit gift cards will be available in $15, $25 and $50 denominations at the retailer's 1,750 stores. That's right, you can now spend real dollars to get fake ones so you can buy imaginary items for games like FarmVille, Bejeweled and 150 other FB games or apps. If that interests you, please contact me. I have some swamp land in Florida I'd like to show you."

http://gigaom.com/2010/09/01/facebook-credits-are-coming-to-a-target-near-you/

Actually my son just sold some imaginery items from the Star Wars game for several hundred dollars. There are kids out there in the inner tubes who have made a small fortune doing this. People who work in offices compete against each other in the gaming world and don't have the time it takes to aquire the items so they buy them from others so that they can be equipped quickly against their oponents.

Demand for virtual goods and services has grown exponentially of late, creating a highly lucrative market opportunity for publishers of social web properties such as social networks, applications, social games, virtual worlds and others. These publishers have found it very difficult to monetize their traffic through traditional forms of online advertising, but virtual goods and services offer them a way to generate significant revenues while simultaneously engaging and motivating their user bases.