We've got a demo unit of an XServe RAID in at work, and it's a neat piece of hardware. I'm not in charge of it, or anything, but I've poked at it a bit, and seeing 3.5TB of storage in that little unit is pretty amazing. We're considering using it with some non-Apple systems, just as an economical method of getting a lot of storage for a small price. AlienRAID is a great resource for this sort of thing, and Apple has certified the unit for use with Windows, Linux, and Netware now. So far, the only drawback seems to be that it takes hours to initialize the disks, but I'm sure that's true of all arrays of this size.