We have one on a linux server at work and are able to query the status of the arrays. The software seems strange and I didn't set it up so not sure on the details. On FreeBSD the array status shows up in dmesg on boot, so I imagine it can be accessed in some way while running. Anyways, for me it is a cheap and high density solution (used cards from ebay) that I am recommending it for.

I can't agree with this enough. My personal server room used to cost me about $60/mo in electricity. Now with fewer and smaller drives and moving a number of things to a single vmware server I've reduced it to about $30/mo. For anyone interested in seeing what things really use, I recommend picking up a kill-a-watt meter for $25. http://www.amazon.com/P3-International-P4400-Electricity-Monitor/dp/B00009MDBU/ref=sr_1_1?ie=UTF8&s=electronics&qid=1247515957&sr=8-1 Of course they can't measure things that are under 15A on a 110v outlet. Higher loads can be measured using one of those loops on a multimeter, but I think you have to isolate and loop around the hot line only which can be a pain unless you are comfortable opening the breaker box while live.

For backups I really like FreeBSD ZFS (with raidz). I rsync in new data from my servers and then create a ZFS snapshot. It works quite well. I have running it at home and at work. Of course the raidz is software so you can use whatever cheap controllers you have around. The thing that makes me love it is that ZFS does its own checksums so it can detect if the data it is reading does not match what it wrote.

Good point about the controller costs. I have been facing a similar problem with my own massive storage setup. One thing I have found that works well is getting Dell Perc 5/i cards from ebay. New they are around $500 or $600. You can get them on ebay for maybe $125. This allows you to connect 8 SATA drives via one PCI express slot. I've only tried it with FreeBSD and JBOD style configuration though.

I am also wondering why this is not in the news. I don't see it on CNN or google news yet. What sort of science editor does not check slashdot?