Not long after the Nintendo DS came out, enterprising hackers are
writing their own software for it. Of course, since Nintendo forbid unauthorised software on their consoles and go to great lengths to prevent the devices from running such code, the hackers have to go to
great lengths to get code onto the device.
I imagine one could do some fairly nifty things with the Nintendo DS hardware if one cracked it open enough to do so; it has two ARM CPUs and built-in WiFi networking (albeit, natively, it runs a weird proprietary protocol on top of that). And that goes doubly so for the new PlayStation Portable.