I'd say the majority of people here are using Unraid or WHS v1. Once you build up a substantial library with WHS v1 there's no upgrade path so I bet a lot of people are still using it. Honestly theres not really any reason to switch. I've got my main media library on Unraid. I use WHS v1 to back up my PC's and store my TV recordings.
So my point was to defend WHS v1 articles as being relevant, then as I'm typing this I realized that the people that will be reading these articles will be setting up new systems. So WHS 2011 should have more prominence, though V1 is still a viable option. I think Unraid should get some serious attention though. For our uses it's perfect. It can run on older cheap hardware, presents a single folder spanning multiple disks, and has some redundancy.
I would seriously gloss over the other 'nix options. For this site the people that are trying to build one of those systems aren't beginners. As mentioned already if you want to get into ZFS or some other options needing the command line they should head over to HardForums. Just stick to the basic options that will help out 95% of the users here. If you start diving into the more esoteric options you'll drive yourself nuts, and you won't even make a dent in covering everything.
I do congratulate you on your effort though. The media server storage thread started out with noble intentions. Educate people on the options, and provide a few example systems as starting points for builds. It never got there. It devolved into hundreds of pages of arguments about $1000 plus raid cards and high end servers out of the budget of all but a few. Then it seemed to die out, and most of those users seemed to have moved on. It never did much good for the beginner just trying to build a simple system. Hopefully you can do better.