How about this one, the Norco DS-520 (Engadget link)?

Five hot-swappable disks, three eSATA connectors, GigE, one giant fan on the back, claims to support Linux, etc. See also, the similarly spec'ed Thecus N5200, which comes preconfigured as a NAS rather than the bare metal of the Norco product.

Either way, you buy one of these things, you're not getting much if any tech support. If you get an HP MediaSmart thing, at least you have somebody to yell at on the telephone. Still, you can imagine the tech support nightmare if you're running something other than Microsoft's OS and you're trying to get past the troubleshooting idiots to convince them that you need a replacement part.

EDIT: Microsoft claims they're not selling Windows Home Server barebones:

Quote:
Why aren’t you releasing the software standalone to consumers?

We want to help ensure customers have a simplified, quality experience with Windows Home Server. The best way to do this is to deliver Windows Home Server on integrated hardware/software solutions through OEMs and system builders that are tested and meet system requirements.