It is now possible to make an exact copy of an audio CD into a single file and be able to play the file as you would from a CD. You can even store the lyrics, cover and more meta-informations in that single file.
I'm glad Matroska (and Matroska only) finally makes this reality come true. That was one of my initial goal :D
All this with open-source technology. That means it can be tweaked and improved with time. (currently working as an alpha state solution)
I also hope this will soon be popular among audio pirates. But for that we'll need to had support for MKA and various codecs in the most popular players : Windows Media Player, Winamp, RealPlayer, Quicktime.