I also don't want to say that any of this is easy.
Open source has a different problem from closed source in the sense that the "sausage making" is visible from the outside.
I don't think that processes or design principles of closed source companies and products is applicable. Is important to prioritize and manage what's happening ... It's just that it's important to do that in a way that makes lets the random person walking-in feel like they've begun to participate rather than giving an answer like "who let you in". (essentially should be the opposite of Linus managing the Kernel).
Perhaps a "friendly bug reception area" would be a worthwhile project. Launchpad may be very functional in ways but I'd say it's very, very broken as far feeling you're participation valued. A random bug thread is "comment-1, comment-2... little-icon-saying-this-is-not-a-bug-with-little-explanation". Just a longer boiler-plate explanation for changes like could be more soothing.