MultiMediaCard to MemoryStick Adapter?

Philipp Markus Alexander Schmid asks: "Does anyone know if there exists a MMC to MemoryStick adapter? There is this wonderful SonyEricsson P800 which comes with a memorystick duo slot. I'm currently building a MemoryStick standard to MemoryStick duo adapter for the phone (because of the non-existing availability of the duo). The next step would be an MMC to memorystick duo adapter, but is there a device or chip that can convert on the fly between MMC and MemorysStick?"