Emerging trends in system design indicate that in the future, a large role will be played by System-on-Chip (SoC) platforms consisting of general-purpose, configurable components. Commercially available SoC platforms provide some degrees of configurability, most of which are limited to one-time (static) customization of platform hardware. However, with increasing application diversity, time-varying requirements, and the convergence of multiple applications on the same platform, there is a growing need for SoC platforms that can be dynamically configured in order to adapt to changing requirements. In this paper, we propose general-purpose, dynamically configurable, SoC platforms featuring multiple configurability options, and illustrate their advantages over existing design styles. We survey technologies that aim at providing dynamically configurable platform components (e.g., processors, caches, memory sub-systems, bus architectures), and associated techniques for exploiting such configurability. In particular, we illustrate how run-time platform customization of configurable, general-purpose platforms using Dynamic Platform Management techniques (using a dual-access UMTS/WLAN security processing system as a case study) can achieve significant improvements in overall system performance and energy-efficiency.