Pressure sensitivity in musical keyboards is nothing new - pressing the keys harder results in a louder note, just as if you sit down with ever-increasing force on a piano - but until now it's not something we've seen on regular QWERTY keyboards. That could all change, if Microsoft Hardware decide to put their pressure-sensitive keyboard into production: developed as a prototype for the UIST 2009 student innovation contest, it can track 8-bit pressure information across all of its keys.
Video demo after the cut
Basically, as well as recognizing when a key has been pressed, the sensor underneath also records the pressure of the press. While you're unlikely to be making music with your QWERTY 'board, what Microsoft envisage is different keyboard behaviors tied into different pressures: so, lightly pressing backspace will delete a single character, as normal, but a harder press would delete a whole word, while an even harder touch might get rid of the sentence or paragraph.
Alternatively you could forget the shift key and capitalize letters by pressing harder, or throw out your gaming controller and use the 'board to make pressure-proportional jumps and other moves. Right now Microsoft Hardware say they have no plans for a production version.