Stephen, I submitted a libvdpau package to debian+ubuntu last month. It hasn't created much interest by the debian folks whom seem rather nvidia suspicious (to do with "free" license).
For Ubuntu, it will be in use for 9.10 and they have already made plan of using this package for the weekly mythtv build.
mplayer , mythtv and other vdpau related program are build agaist the libvdpau package in my repository :
www.avenard.org/media