By default I think Code::Blocks installs its pluggins to /usr/local/share/codeblocks/plugins. I used the --prefix options to put codeblocks in /home/<user_name>/apps/codeblocks-svn, so then your pluggins would be in /codeblocks-svn/share/codeblocks/plugins. This enables you to develop plugins as a non-root user, something that is very advised.