The “machine” is a web service that Amazon is calling “artificial artificial intelligence.” If you need a process completed that only humans can do given current technology (judgment calls, text drafting or editing, etc.), you can simply make a request to the service to complete the process. The machine will then complete the task with volunteers, and return the results to your software.
Volunteers are paid different amounts for each task, and money earned is deposited into their Amazon accounts. Amazon keeps a 10% margin on what the requester pays.
Read more: Techcrunch