PC Magazine reports: "The server was designed to be a thin version of the full-fledged Windows Server, which typically uses an Intel Xeon or AMD Opteron server processor as a foundation for enterprise software. According to a preliminary spec sheet released by HP, however, the new MediaSmart server will only require a relatively slow 1.8-GHz Sempron, AMD's version of the low-cost Intel Celeron processor. The spec sheet does not list the amount of DRAM included in the machine."
I need to build one of these servers before I comment on it. The idea for a home server is not new by any means but what Microsoft has done is legitimized it. I believe there is going to be several product that build on this idea and make it better.