Amiga, Inc./Hyperion VOF has already released Amiga OS 4.0, and it's sequel Amiga OS 4.1. It runs on the Sam 440ep, as well as the classic Amiga, and AmigaOne computers (and Pegasus now as well if I recall correctly). The OS has been rewritten from the original version to support the PPC platform, but it appears to need a separate release for each individual platform (driver reasons maybe? I don't know.). As of now, it doesn't support any modern high-speed CPUs and the newest graphics card it seems to support is the Radeon 9200. It is not a secure machine; memory protection is merely an option which individual programs can decide to opt-in only if they want to.