Spintronics is a class of technology that is similar to electronics, but instead of using the charge of electrons to operate, they use the spin of electrons. This difference opens up a host of possibilities including ultra-low power computing and true instant-on capability for devices. Now researchers at City College of New York have found something else spintronics can do that electronics cannot; rewrite their circuitry.
Using a laser, the researchers were able to control the nuclear spin of atoms in a semiconductor. By aligning the atoms, and their electrons, within a material like this, a circuit can be made on the fly. Though this may be an extreme example, imagine changing the circuitry in your CPU to make it a GPU. Perhaps one program needs a high clock speed and low thread count while another program is the opposite. Potentially you could see the circuitry rewired to provide whatever it is that you need.
This is not something you can expect to have access to any time soon though. Spintronics are still in development and this capability may be something left out of regular commercial products, at least in the beginning.