In this paper we will demonstrate that dynamically reconfigurable computing is the key technology to enable small and energy-efficient hardware platforms for wireless communication systems, which provide the flexibility needed for keeping up with evolving standards and protocols. Two application-specific dynamically reconfigurable systems for WLANs and wireless sensor networks will be presented. The first architecture clearly shows that highly dynamic reconfiguration approaches can provide flexible and high-performance hardware platforms that are smaller than standard ASIC solutions. The second architecture serves as a case study for the design of energy-efficient dynamically reconfigurable computing systems.