Unfortunately, the article is as light on details of the internal components as Promises' so-called datasgeet at
http://www.promise.com/upload/datasheet/NS4300NDatasheet_20080709.pdf
I would really like a thorough investigation of the internals, including the processor (it's a SoC, but which one), controller chip, and underlying OS. I suspect that it is a BSD derivative due to the lack of published source code available on the promise website, though "Billy" from the promise NAS focus group seemd to indicate that it was Linux using a special promise RAID technology (and not LVM or MDRAID)
There are multiple posts on the avsforums regarding the unit. Of the 25 or so pages that I read, I found that the unit is not a stellar performer, and can be purchased for around $300.
Ultimately, it looks as if you're better off purchasing a full featured $200 Atom based platform, tossing in 4 disks, and utilizing linux LVM/MDRAID for a full fledged NAS.
Frank