The first screen includes a recommendation engine that tries to divine what you want to watch based on your viewing habits. It can pick from the current TV programming of your cable or satellite provider.
The third panel gathers all your local media, whether from DLNA sources, connected smartphones or tablets, or plugged-in USB media. The fourth (not shown) is a social interface for, yes, tweeting from your TV.
Just plug the module (price TBD) into the back of a compatible 2012 Samsung TV and it will upgrade to the new Smart TV interface, complete with a faster processor and more memory. The company also throws in the latest, improved version of its touch remote control.