Pocket doors are used all over the house. Most commonly used in turn-of-the-century homes, they've become more common because of their space-saving construction. Unlike sliding doors, pocket doors actually slide into the wall, rather than along the side of it.
Great use of a stair landing! An inviting reading nook!! I'm sorry I can't give credit to the source - I had this pic saved on my computer. I love the casual striped walls, the color palette, the natural light.