ReadWriteWeb has more: “Simply adding in-app purchases to the API has allowed developers to develop creative ways of monetizing their games, Yerga said, allowing so-called ‘freemium’ and ‘paymium’ models to succeed. For example, developer TinyCo., developer of ‘Tiny Village,’ said that Android delivered the most revenue per user of any app store, as users downloaded the free app, then purchased virtual items.”

Google Play, which has more than 600,000 apps, recently crossed the 20 billion download  mark. And yesterday, the online giant began pre-selling a new tablet device called the Nexus 7, which is to Google what the Kindle Fire is to Amazon, a device for users to buy and consume digital media content.