I've been building Debian packages of the mplayer.git snapshots. The packages are based on a slightly modified version of Christian Marillat's mplayer packaging. These packages are working pretty well for me and have some new features relative to the main mplayer tree. Most importantly, they support Matroska linked segments and ordered chapters.

Hopefully this is just a short-term measure until these features finally enter the mainstream packages. My packaging can be found here: http://www.gnifty.net/code/mplayer/