I didn't follow the discussion really closely, but I don't know how many plugin authors would like to use such a repository ? Maybe as a first step, reworking the
live.gnome.org rhythmbox plugins pages and making it easily accessible from
rhythmbox.org would be good enough ? Anyway, don't let the lack of feedback stop you, if you feel strongly about that, you should start experimenting with such a repository and send other mails when you have built something which rocks :)
Cheers,
Christophe