The penetration of mobile device in western countries is still increasing. The Italian case is really surprising: every single Italian has more than one mobile terminal. Thus, considering this large potential audience, there is real need for innovation and new services. In this context, usable multimodal services could have an unexpected impact on social behaviour. Nevertheless, the research community should be able to propose a framework for building generic multi-modal services, covering all their lifecycle. We are currently defining an architecture for building coordinated simultaneous multimodal applications trying to use as much as possible open source software: our goal is to define a set of tools for enabling a rapid deployment of a generic multimodal service. In our opinion, a platform based on open source software could meet the expectations of a large numbers of service developers. A special effort for enabling a mass diffusion of mobile multimodal services should be focused on the client side, where the situation is still evolving.