craeonics - there is a screen being developed which does just that. Based on the same sort of technique as those flip cards with 3d looking pictures on (in?) which used to be given away with breakfast cereals. It may never turn into a real product though as holographic projection may well deliver soon enough to usurp it.
...and you can of course have stereoscopic glasses now (either the LCD alternating eye type, or with 2 displays built into them) - these can be linked to a VR set up which monitors head movement etc to create a 3d (4d as you noted) environment.
...the bit that's missing isn't the display devices - it's the OS which supports them

Microsoft used to have a whole sub site dedicated to their work investigating adding a 3d metaphor to the desktop - last time I looked though it had been removed. It was looking dated though.