Much of the work currently being processed is for nonprofit cancer researchers. Currently, organizations who can contribute a minimum of 25 nodes (think university computer labs, or office buildings full of workstations -- where there are dozens of computers sitting idle ~16 hours a day or more) may qualify to receive compensation for their computing power. For qualifying organizations, earnings are based on the amount of time a computer spends processing tasks for paying clients, the power of each computer, how often it connects to the Internet, and the speed of the Internet connection.
As the program grows and more commercial researchers use Compute Against Cancer, we expect to extend that offer to individual providers, whether they contribute one computer or one hundred.