From Yamada Tatsushi:
PowerRUN enables applications to be moved from internal memory to a Memory card and enables them to be launched from the Memory Card (Memory Stick, MMC, SD Card, CF card etc..) as if they resided in internal memory. PowerRUN may be used to free internal memory by moving infrequently used software to the Memory Card. More frequently used software, or software with large databases such as dictionary or mapping software may also be moved to the Memory Card, but may take longer than is convenient to launch.
Features: Applications may be moved to the Memory Card from internal memory with ease (and vice-versa). Launching a memory card application is fast. Third party launchers may be used. Applications and also attached data files may be moved to the memory card. Read/write databases may be moved to the memory card (The OS standard software only allows read only databases to be moved). Applications on the memory card may be categorised like those in internal memory.