We've created some new support channels for mosquitto - a mailing list and an irc channel. Although they are both intended for providing support for mosquitto itself, general discussion of anything to do with mqtt is strongly encouraged. We want to reduce the barrier to getting started and provide a place where people can share their experiences.
The mailing list is at http://launchpad.net/~mqtt-users
The irc channel is #mqtt on the freenode network