Dr. Raskin was one of the first human interface experts to contribute to and be involved in the Apple Macintosh. computer. While it's true that the design took a different direction from some of his initial ideas, he played a major role in defining the user interface ethic of the Macintosh, and consequently basically every other major computer interface.
After leaving Apple, Jef went on to continue his ideas with the SwyftCard and Canon Cat. The best articulation I've seen of his ideas regarding interface design is in his book, The Humane Interface. He has also put a great deal of his work on his personal website.
This is a sad day, indeed.