Some nice people at UserVoice took the time to jot down how they manage their product. Amongst the lessons learned:

This, to me, is an interesting juxtaposition. Normally, I think of bugs as things that should all be fixed, eventually. Putting some scarcity of labor into them is a great idea. Fixing bugs is great, until it negatively affects morale. Better to address the most critical and pressing bugs and then move the product ball forward. A mechanism to limit the number of bugs to fix, plus the feedback loop of recognizing those who fix bugs in an iteration (they mention this elsewhere in the article), is a great idea.