Here is a headline I could not have imagined 10 years ago as anything other than science fiction or satire:
Dutch police arrest teenage online furniture thief
Apparently there is some kind of teen social networking site called Habbo Hotel that allows teens to outfit their rooms with virtual money, which they buy with real money.
This illustrates that there a two tests to validate that something in the virtual world has real monetary value. 1) If someone is willing to purchase it, or 2) if someone is willing to steal it.