Ultimately, your decision of where to go first (between the two) will be based on the software expertise that your team has. Apple is undoubtedly a fantastic platform for developing apps. It provides great tools and has implemented a very effective worldwide distribution network. Publishing apps for iPhone, iPad and iPod Touch can be a lucrative market, and the ability to develop apps that are universal (buy once and then use on all your Apple devices) is a big plus, particularly for children's book apps. With Apple, all apps must meet the App Store Review Guidelines and are reviewed before they are published. This is a good way for Apple to regulate what is on the App Store, eliminating apps that either crash or have content that is objectionable. The primary downside to iOS is that the Apple App Store is extremely crowded. It is tremendously hard to get visibility for new apps. For those looking to have fewer rules and a larger target market, Google allows you to publish anything you choose on the Android Market with no review process. The catch is that with the large number of devices from different manufacturers that support a variety of operating systems and hardware specs, Android makes app development much more complex and expensive. Testing Android apps alone, for example, can be a nightmare. That said, the Google Android market is growing at a quicker pace than the Apple market, and industry sources predict this will continue for the next several years.