Koko,

The USPS has a small distributed processing setup in every mail processing plant for image processing made up of 20-200 pizza boxes, each box being a quad core linux box with a master parceling out work based on response time and load monitoring. They communicate through a gigabit copper network.

Required result response time back to the originating sorting platform is 320 ms, and the system meets that mark 95-96% of the time. Our site is tiny, it's only set up to process about 150,000 images per hour. It's amazing what distributed processing can accomplish.