I use Gearman entirely as a point to introduce asynchronous-ness in my application. There is a complicated and image-heavy PDF to generate and this happens on an automated schedule. To do this, I use the GearmanClient::doBackground method. This inserts a priority 1 job into my queue.
doHighBackground() and the
doLowBackground() methods insert jobs into the queue and checking out my persistent storage I see that the priorities work like this:
Gearman works out which task is the next highest priority and will hand it to the next available worker - which means that I can set my automated reporting lower priority than the reports requested by real live people wanting them now, and everyone is happy!