My fav thing about this community is that it's focused on sharing ideas and the mods do a great job of keeping it spam-free. All sources of great resources are being shared within the group for this interested in publishing and/or learning about the process.
The G+ group does a great job at limiting spam as well but what makes it special is how responsive the G+ team is in addressing user questions/concerns. It'd be impossible to respond to everything but there is a clear presence that is much appreciated.
I'll admit I helped start this community, but it's a great place for Community Managers to come together and share content and ideas to help improve their own communities. I love how many people have joined arms already.