The forthcoming wireless systems beyond 3G are heralded to trigger dramatic changes in the way that mobile services are being developed and delivered. User expectations are expected to raise to a significantly higher level, towards the demand for terminal-, network-and location-aware provision of ubiquitous, personalized multimedia services. Adaptability, a feature that did not attract particular attention from system and service developers of services in the pre-3G era, is widely recognized as a critical factor for realizing this vision. The present paper discusses adaptation of end-user services provided over next generation mobile systems, identifies relevant important issues and introduces a mechanism for deployment-time, application-transparent adaptation.