Even if you have a beautiful workspace, it may clutter up the landscape of a connecting room. Nexus Designs decided to solve that problem by hiding this workspace behind a moveable wall.
The wall is a very simple grey panel that slides on rails, providing access to an otherwise hidden space. Even if it might be slightly more cumbersome than a door, it's pretty cool to be able to say that you have a secret home office. The only thing that might make it more awesome (or dorky) is a motorised opener with a candlestick level -- but that wouldn't really fit into the contemporary, minimalistic design.
While this may not be in the budget of every reader, Apartment Therapy Tech suggests an alternative: use a curtain. It's not quite as stealthy, but it worked well enough for the Wizard of Oz for a good while.