We have always accepted server patches via the mailing list: https://lists.rabbitmq.com/cgi-bin/mailman/listinfo/rabbitmq...
But it's true that the community has been much more involved in clients like Pika, for example.
And yes we are planning to open up the bug tracker.
A piece of advice for anyone doing an open source project - start with an open tracker, because opening up a previously closed tracker is a royal pain in the butt.
And while we don't use github internally, people can and do submit issues and pull requests there:
(N.B. we need contributors to sign a contributor agreement.)
David (rabbiteer)
Btw, I'm using RabbitMQ, and I love it. My needs do not include high load or high availability though so I can't speak for that. So what's nice about it? AMQP (you automatically get lots of tools, docs, "expectations", etc), very friendly and active mailing lists, small & clean code base, small footprint, simple, active (more features are always being added).
What I don't like about RabbitMQ? While it's FLOSS inside out, its development isn't exactly a "community" work. For example, I can't report an issue, attach a patch, and receive a reviewer/committer feedback about it and possibly get it in. In fact, I can't even report an issue into their issue tracking system -- I just have the mailing list. That said, I believe they said they are going to fix that part "soon".