The document discusses how to earn money by developing apps for the Windows Phone Marketplace. It provides statistics on the Marketplace like the number of apps and downloads. It outlines the steps to submit an app, including using a trial period and integrating advertising to increase downloads and conversions. It also recommends using the Marketplace API, reports, feedback and Runtime Intelligence to improve apps, marketing and user experience. The overall message is that developers can earn money on the Marketplace by thinking about marketing, trials, ads, feedback and analytics.