Looks like a nice API (in a few languages) on top of some basic AMQP functionality backed by RabbitMQ. We're building something rather similar (for internal use

Looks like a nice API (in a few languages) on top of some basic AMQP functionality backed by RabbitMQ. We're building something rather similar (for internal use, not a product). Might have to keep my eye on it, though it's hard to tell what it would cost for server licenses from the webpage. The core server is closed source with rate-limited free binary downloads.