The hype surrounding Web 2.0 and technologies such as AJAX shows: The future of distributed application development lies in Rich Internet Applications (RIAs), which are based on highly distributed components and characterized by the intensive use of communication networks, complex interaction patterns and advanced GUI capabilities. As service providers begin to tap into the mobile market by extending the reach of their established e-commerce systems to mobile devices, a core challenge is the choice of a runtime environment and middleware that adapts well to the existing architecture, yet is a safe investment for the years to come. This paper surveys the current state and the future of runtime environments suitable for developing RIAs for mobile clients.