Since last week the bzr-playground machine has been setup as a syncrepl consumer. This means that all SSH key changes (plus new accounts) will automatically be able to use bzr-playground. Note: I mean to host private branches, of course people SSH is optional if people either commit to svn.gnome.org or just attach the result to a bugreport.
Bzr-playground is usable for anyone with SSH keys set in their GNOME ldap account; it is not restricted to just people with SVN access. Also, the LDAP replication is minimal, the bzr-playground server knows little more than usernames + public SSH keys.