I've been using Beanstalk to handle the export queue for Mockingbird for the past few months now. It was super easy to setup and has been very stable. I'm a huge fan of these easy to setup/lightweight tools - people who design software for programmers should have the same attention to user experience that people designing software for non-technical users have. When queuing jobs isn't the hard part of my technical problem, I don't want to spend a lot of time configuring things I don't care about or learning about stuff I don't really need - Beanstalk was great for this.