How is the work to be done scheduled and otherwise managed? Do you need to be able to kill tasks once they start executing. Do you need to be able to remove tasks from the queue? Is it sufficient to have a single "reliable" system as the manager or should the management be distributed in some fashion? Do you require task result reporting? Do the tasks have to contend for central resources?

An "easy" way to do something like this is to use an email server to manage the queue. The task servers then check the queue from time to time and fetch tasks by reading and deleting an email from the queue. Because the email can contain pretty much anything it is easy to tailor tasks and distribute any information that is required for execution of the task.