Multiple core systems isn’t new thing for quite long time. Probably your desktop or laptop computer is equipped with at least two core processor. Multiple cores simply share workload of the system. For instance two cores can perform two complex tasks in real parallel and so on. In other hand we don’t see much multicore systems on microcontroller area especially on 8-bit ones. So Jack Eisenmann have built a nice multicore implementation using sixteen Atmega328 microcontrollers.
Computer uses one Atmega328 as manager core which coordinates other “worker” cores and uploads byte codes to them. IT also takes care of interfacing Ethernet shield, shared 32KB RAM and 512KB Flash. Also for user interactions there is a VGA output and keyboard interface. As demonstration shows, multicore 8-bit computer has more processing power that single AVR could provide. Demo software gives a clue about speed by generating Mandelbrot fractals, also finding primary numbers. Probably you cannot compete much with ARM systems, but with low price of Arduino chips it makes quite interesting play. If you want to look deeper in to this, Jack has made a great description of bytecode specs and even provides a web based emulator to give a try.