The iPhone and Google Android platform are undisputedly transforming the mobile industry by bringing smartphone capabilities to the masses. They are also making for enticing new mobile platforms for developing and deploying new types of mobile apps and services for mass market users. Yet, developing for them is not that easy. This session will focus on our experience of developing open source-based mobile messaging and sync applications for both of these platforms. It will compare and contrast the platforms in terms of the development methods and tools required, and their strengths and weaknesses from a developer's perspective. The presentation will share lessons learned as well as tips and techniques for developing for both platforms.