I’ve run into this now a couple of times. The cause may be from the (sometimes) default binding to 127.0.0.1 in the rabbitmq-env.conf file. Update the file, changing the value of NODE_IP_ADDRESS to 0.0.0.0 which will bind it to all IP addresses on the machine. Or you can bind it to just a specific one.
http://superuser.com/questions/464311/open-port-5672-tcp-for-access-to-rabbitmq-on-mac