SpamCop is (was) open source
Open source development of SpamCop never took off, so it has been discontinued. It continues to be developed exclusively by Julian Haight.
An old version of the spam-reporting side of SpamCop is available under the GNU General Public License (GPL) from sourceforge. Most of the links here lead to sourceforge pages. Thanks to the folks at sourceforge and valinux for providing this powerful free service.
If someone is interested in taking over the GPL version, please let me know.
Source availability (sourceforge links)
Developers who would like to contribute code should obtain sourceforge accounts and then post to the developer newsgroup.