This is an early-stage prototype that a friend is making for me. That piece of aluminium is used as a bridge that spans the screen and gives the user something to rest his/her hand on. In-app palm-protection? Meh.
There will be hinges at the top so that the arm-rest swings up to reveal storage for cords, styluses. Home-button will be accessible without lifting lid. The screen is not quite as "sunken" as the picture suggests.
It's not meant to be portable. It's just to enable me to write, draw and type on the iPad comfortably for long periods at a stretch.