Robots are going to do many things for us in the future. They are already capable of cleaning windows. The HOBOT-298 is a window cleaning robot with a 24 x 24 cm cleaning cloth and can clean 40m2 area before you need to refill the water tank.
This robot can cover one square meter in 2.4 minutes. It has laser sensors to detect the distance to work on. It is driven by a brushless DC motor. You can monitor everything from your smartphone.