[abritinthebay]

> I struggle to remember anything he's created or written that's moved the needle

Well he helped created the first computer networked workstations, practically invented Object Oriented Programming, created the concepts of overlapping window management...

... I struggle to think of what needle your trying to move that wouldn't be moved by any of those.

[Magicator]

Also, more recently, his work with the Squeak Smalltalk and Scratch communities, particularly regarding computer programming education for children, is certainly currently relevant. His is one of the finest minds I have yet experienced in person.