Why do we need RabbitMQ when we have a more powerful network framework in Python called Twisted. I am trying to understand the reason why someone would want to use RabbitMQ. 
Could you please provide a scenario or an example using RabbitMQ?
Also, where can I find a tutorial on how to use RabbitMQ?
RabbitMQ is a bit more than mere messaging... It's a common platform that has ability to inter-connect applications. Using RabbitMQ a Java application can speak to a Linux server and/or a .NET app, to a Ruby & rails + almost anything that finds its place in the corporate web development. And most importantly it implements the "fire and forget"   model proposed by AMQP. Its just a perfect replacement for JMS or ESB, especially if you are dealing with cross platform architecture, with a guaranty of reliability. There is even a special feature called RPC (Remote procedure call) that adds to the ease of development in the distributed arch. 
Apart from all these, in the world financial services like Stock-exchange or share-market where a lot of reliable and efficient routing is required (suppose you don't know the actual number of people subscribed to your services, but want to ensure that who ever does so, receives your pings whether they are connected in this moment, or will connect later), RabbitMQ rules because it's based on ERLANG & the Open-telecom platform that assures high performance while using minimum resources. For the most convenient introduction to RabbitMQ, see rabbitmq.com/getstarted.html for your native development language.
Why do we need to use rabbitmq