zypper ar http://download.opensuse.org/repositories/devel:/languages:/erlang/openSUSE_12.1 erlangNow you probably want to do some configuration and provisioning using the rabbitmqctl command; but your RabbitMQ instance is up and running.
zypper in erlang
rpm -Uvh rabbitmq-server-2.8.1-1.suse.noarch.rpm
service rabbitmq-server start
Update 2012-04-10: Updated these instructions to install RabbitMQ 2.8.1. The later 2.7.x series have start-up script issues as those scripts use the "runuser" command which is not present on openSUSE. Running the latest RabbitMQ is generally a good idea in any case, recent versions have corrected several memory leaks and manage resources more efficiently.