This is old news but these Stanford academics are doing some remarkably interesting stuff with light field cameras:
Photographs digitally refocused at different depths, computed after a single exposure of our light field camera. The fourth image shows what a conventional camera would have produced.
Imagine if the focus distance was just another bit of non-destructive metadata recorded by the camera. In post, sharpening an out-of-focus image would be as simple as shifting the focus distance metadata.