The variety of mobile operating systems, devices, form factors, and middleware technologies make an implementation that simply extends existing websites impossible, as do the time-to-market and user experience demands. This report clarifies the mobile development landscape and highlights the options available to application development and delivery (AD&D) pros and where the market is heading over the next 12 to 18 months. This is an update of a previously published report; Forrester reviews and updates it periodically for continued relevance and accuracy.