Distributions in the *Ubuntu ecosystem support proper RGB subpixel rendering in Mono based applications (e.g. Banshee) by default, i.e. out of the box without any additional configuration requirements, whereas e.g. Fedora does not. I am aware of general patent infringement issues and the freetype-freeworld libs, but never managed to enable RGB subpixel rendering for Mono in Fedora - it keeps using greyscale.
So, as the question title implies: how does *Ubuntu achieve RGB subpixel rendering in Mono applications?