Subversion is an advanced version control system. This page provides some information on the state of Debian's Subversion packages.
To see what packages are available in different Debian releases look here.
A backport of Subversion for the current stable (Sarge) release is available at backports.org.
Subversion's progress into Debian testing (a required step for Subversion to appear in a stable Debian release).
More information such as build logs, bug reports and general status can be found in the Package Tracking system
If you would like to help maintain Subversion in Debian the packages are maintained in the subversion repository. Anonymous access is available here:
svn co svn://svn.debian.org/pkg-subversion/trunk/ pkg-subversion
Or you can browse the repository here: http://svn.debian.org/wsvn/pkg-subversion