It's a huge pot, and analysts are betting it will only get bigger.
A report published today by Britain's Juniper Research estimates that wagers on mobile gambling will top $48 billion a year by 2015.
The Mobile Gambling Markets report says the Japan Racing Association's iPAT service is currently responsible for most mobile gambling transactions, with services in the UK accounting for much of the remainder.
However, it predicts the surging mobile lottery service launched by VODone will propel China into third place in terms of mobile gambling transactions.
The U.S. market is poised to see the introduction of its first mobile lottery services and the report says impending legislative changes in the U.S. may kick open doors for mobile casino operators in the medium term.
The report also notes that while Apple is now allowing gambling apps to be sold via the App Store, most service providers are opting for a browser-based approach.