From the website:

The Media Grid is a computational grid platform that provides digital media delivery, storage and processing (compute) services for a new generation of networked applications. Built using Internet and Web standards, the Media Grid combines Quality of Service (QoS) and broadcast features with distributed parallel processing capabilities. Together these features create a unique software development platform designed specifically for networked applications that produce and consume massive quantities of digital media. The Media Grid is powered by service providers (such as rendering farms, clusters, high-performance computer systems, computational grids, and similar systems) that furnish on-demand services to Media Grid clients (users).