Interesting work from Chris Harrison at CMU's Human-Computer Interaction Institute.
The research centers on a fundamental issue I've been contemplating:
Physical buttons have the unique ability to provide low-attention and vision-free interactions through their intuitive tactile clues. Unfortunately, the physicality of these interfaces makes them static, limiting the number and types of user interfaces they can support. On the other hand, touch screen technologies provide the ultimate interface flexibility, but offer no inherent tactile qualities.
The dynamic nature of digital displays allows for effective feedback loops, in which an action is taken in a context, affecting and 'resetting' that context ready for a new action. This affords the 'ultimate interface flexibility' referenced above, but is predominently visual (and in some respects also aural) in application and execution.
Tactile interfaces can be precise and definitive, but offer a dearth of flexibility and little in the way of resetting context for a new interaction. Buttons and sliders and dials don't vanish or move or shapeshift.
Breaking out of the visual/aural shackles into the tactile or spacial is something of a holy grail, and this work on 'pneumatic displays' is an intriguing exploration. It still feels constrained to me though – the dynamism they're acheiving is within relatively narrow bounds.
In many ways this loops back to my post on Tangible Bits and Radical Atoms. Imagining dynamism in physical objects is hauting my dreams at the moment.
Lots of other interesting work coming out of CMU's Future Interfaces Group.