There are these packages in _unstable_ which you probably want to install:
* [[xserver-xorg-video-nouveau|http://packages.debian.org/unstable/xserver-xorg-video-nouveau]] The 2D DDX
* [[libgl1-mesa-dri|http://packages.debian.org/unstable/libgl1-mesa-dri]] The 3D drivers
Other packages will automatically be installed as dependencies, such as
* [[libdrm2|http://packages.debian.org/unstable/libdrm2]]
* [[libdrm-nouveau2|http://packages.debian.org/unstable/libdrm-nouveau2]]
Newer versions of these packages are occasionally available in Debian's [[experimental|http://wiki.debian.org/DebianExperimental]] repository.
If you run into problems, you may want to install various -dbg packages to debug them:
* [[xserver-xorg-video-nouveau-dbg|http://packages.debian.org/unstable/xserver-xorg-video-nouveau-dbg]]
* [[libgl1-mesa-dri-dbg|http://packages.debian.org/unstable/libgl1-mesa-dri-dbg]]
* [[libgl1-mesa-glx-dbg|http://packages.debian.org/unstable/libgl1-mesa-glx-dbg]]
* [[libdrm-nouveau2-dbg|http://packages.debian.org/unstable/libdrm-nouveau2-dbg]]
* [[libdrm2-dbg|http://packages.debian.org/unstable/libdrm2-dbg]]
* [[xserver-xorg-core-dbg|http://packages.debian.org/unstable/xserver-xorg-core-dbg]]