Lastest source tarballs can be downloaded from SourceForge Releases
TUT is developed using Subversion, hosted on browsable SourceForge Repository.
You can checkout the code using svn command line client
svn co http://tut-framework.svn.sourceforge.net/svnroot/tut-framework/trunk tut-framework
If you want to participate, please create your patch against latest trunk version and state revision number when submitting.