I'm a bit confused. The more i read the doc, the more i feel it look Just Another Queue system. I don't really see the difference between Kafka and let's say RabbitMQ, Celery or also statsd...
There are differences, the biggest of which is throughput. Kafka can handle incredible load. The messaging semantics are also a bit different. Here's a pretty good comparison:
http://www.quora.com/RabbitMQ-vs-Kafka-which-one-for-durable...