I've used that for
several other collaborations. It's free and easy to use and keeps
history. Also it does a nice job preventing spam and "out-of-office"
replies and is really easy to use. I think it also digitally signs
(DKIM) messages to aid delivery (so mails are not marked as spam). It
has good sign-up/leave tools as well and various permissions for how
public messages are and for hiding email addresses from the public:
http://groups.google.com/
I don't know the history of this project, but I don't see Sourceforge
in your list of options for hosting. For any open source project,
they host free source control, a wiki, a bug tracking system, forums,
and a download section. I've used it to collaborate on other projects
and it worked great.
http://sourceforge.net/create/
I'll gladly set up either one if people are interested.