The mobile industry is worth over $1.3 trillion annually with over 1.6 billion mobile phones sold in 2011. There is significant hardware fragmentation across the over 680,000 distinct Android devices. Developing apps across the top 4 mobile platforms (iOS, Android, Symbian, Blackberry) reaches only 20% of devices. Mobile platforms differ in their programming languages, development environments, and app stores. No single cross-platform development tool supports all mobile platforms, and mobile web apps face challenges of fragmentation, performance, and monetization.