As the co-founder of
http://askmarkets.com let me add that Predictify seemed to have huge operational costs, and the business model of running public play-money markets, with no specific focus remains to be proven sustainable. Moreover, it was more of a game and less than a market (prediction or not). So far, only real money public markets (Betfair, Intrade) and marketplace-as-a-service providers (Newsfutures, Inkling, Consensus Point) are performing well enough, to my limited knowledge.