Info Value = the added accuracy the markets provide relative to other mechanisms, times the value that accuracy can give in improved decisions, minus the cost of maintaining the markets, relative to the cost of other mechanisms.
A highly accurate market has little value if other mechanisms can provide similar accuracy at a lower cost, or if few substantial decisions are influenced by accurate forecasts on its topic.
Wow, great formula. [BTW, I have slightly edited RH's first sentence.]
I’m sure Mike Giberson will write another blog post for Midas Oracle about that formula —all that for free. Crowd-sourcing works for me. 
Do Google’s enterprise prediction markets work?
http://www.midasoracle.org/2008/03/26/google-enterprise-prediction-markets-4/