The notion of application – a single, bounded piece of functionality presented to users – goes almost unquestioned. However in the context of highly adaptive and ambient systems it is not clear that pre-building and pre-packaging functions is useful, and it may be that a more dynamic model of providing functionality is required. We re-assess the traditional notion of packaged applications, and instead explore a dynamic model of component composition. The model is naturally adaptive in the sense that services “self-assemble” in direct response to user needs, environmental factors and information relationships. We explore some ways in which this might change the way we think about adaptability in ambient systems, and sketch some directions for the future.