Debian GIS is a “Debian Pure Blend” with the aim to develop Debian into the best distribution for Geographical Information System applications and users.
A good deal of GIS related software and libraries (e.g. GRASS GIS, GDAL, and PROJ.4) are already present in Debian.
Thanks to efforts of the Debian GIS team, we currently have many exciting GIS packages in Debian's main archives. Other programs are well along their way to being included in the archive.
The Debian source packages maintained by the Debian GIS team are also used by efforts to support current GIS software on Debian derivatives such as UbuntuGIS, which provides backports of GIS packages for Ubuntu, and OSGeo-Live for their Ubuntu based distribution.
The Debian GIS team collaboration infrastructure on Alioth originates from the initial team effort to maintain the grass package. It has since grown to collaboratively maintain most GIS and OpenStreetMap source packages, but still uses the pkg-grass group name on Alioth.
If you want to join the group you need to register an account on alioth and ask for being added to the pkg-grass group, preferrably by sending a short introduction mail to firstname.lastname@example.org.
Please don't forget to read the documents below! (Specifically the Debian GIS Policy)