I just found an old thread about this. I think this still sounds like a great idea, go checkout the original thread http://forum.vectorlinux.com/index.php?topic=10455.0
It sounded like the primary drawback at the time was administrative/server overhead.
This would be a great use for branded-gmail aka "Google Apps for Your Domain". It is free for non-profit orgs and I have set this up before for my domain wholebean.info. Just like gmail, users who prefer an offline client can access via POP/IMAP.
Everything is hosted by Gmail, and users have access to the full suite of tools such as calendar and docs (Could be good tools for devs to use coordinate?). New account setup can be handled by any one of a number of deligated "admins" through their simple webadmin panel.
Even subdomains can be used to setup accounts such as @dev.vectorlinux.com or @supporter.vectorlinux.com