GNUstep has moved from CVS on savannah.gnu.org to SVN on gna.org.
Although it is recommended to use released version of GNUstep,
here is how to check out the SVN version:
For gnustep-core with svn protocol:
svn co svn://svn.gna.org/svn/gnustep/modules/core gnustep
This is an example for GWorkspace with http protocol:
svn co http://svn.gna.org/svn/gnustep/apps/gworkspace/trunk gnustep/apps/gworkspace