Reaktiv Studios has released Locomotive, which is their take on batch processing in WordPress.
When you register a process, you define the parameters of your data query, using all of the arguments available to you in default WordPress queries. Then you set a simple callback function. As Locomotive runs your query, it iterates through the array of data, and passes each individual object to the callback function, where you can process it however you want. Locomotive then chunks the data into individual steps, and streams the results live as they are processed.
They are calling it an “early beta”, but I’m really excited about what I see so far. It’s on Github, ready for you to test it and help them improve it.