What's a good alternative? The spam problems in Google Groups totally suck, especially for very active groups, but it's a familiar system, so even non-techies can sign up and post fairly easily.
I was thinking of the same thing. What is really needed is a clean group management solution with a nice inviting UI, a good spam filter (something like Akismet) and good access control for various levels of admins. The last would really hit it off with open source projects having a BDFL sorta guy with multiple pillars.
It could even be freemium with free access to public groups involved in open source projects. Maybe even some nice integration with whatever seems logical.
I'd kinda like to see either the Groups team fix the problems or some startup come up and really own that space.