Router/network device Question

BenjaNinja

So I was doing some more reading up for the net+ exam and I did brief side study on network hardware devices and the differences between them (hubs, switches, repeaters, routers, etc...)
My question is this- unless I'm mistaken, switches, and bridges both "sort" data based on the MAC address. However, for routers the data is sorted based on IP address. I heard one reference say this was to "allow transmission between different protocols", but do IPX (or other protocols) use IP addresses? If no, why the change from MAC to IP routing?
Thanks
Ben