People often thinking about topics they want to learn. People are often lazy to get up, focus and put some time in learning.
What happen when your friend or colleague tell you that he learned something or learning something. You get motivated, interested or get competitive for learning that too.
This is simple widget/app that shows you notification when somebody learned something new, or is in process of learning. In the app you can check the box that you learned something, or you curently learning about. (You can add note about what you learnd or learning) other users will get your notification on their phones.
How would you stage or advertise your hack?
It can be seen as a simple social network. You will not spend time on it, but it will triger interest. Maybe to start learning by yourself, or contact the colleague to speak about same interest, motivate and potentialy learn it together.