No, it's not "All you computer belong to us" see here:
http://opensimulator.org/wiki/Downloads
linux standalone runs with mono prebuilt.
Working fine here. (Well, fine as can be expected after following the instructions)
Only the REX viewer and sever must be run on MS gear. AFAIK
I need only reboot to use rex and make big prims. After that, I can move and texture but not resize any.