I've found two URLs gvien for SVN:

https://developer.berlios.de/svn/?group_id=4265 - http://svn.berlios.de/svnroot/repos/zenphoto/trunk

and

http://www.zenphoto.org/support/topic.php?id=138#post-672 - http://svn.berlios.de/wsvn/zenphoto

Neither work for me. Any suggestions?

Use the top one, but get rid of trunk.