Theories abound (I have my own) about why it did not happen long ago, but at last Lamport did receive the Turing Award. For me what most characterizes him is a stream [1] of elegant, original, insightful articles providing solutions to one important and thorny problem after another. Some of these articles are well known but many gems are not; see for example his take on Buridan’s Ass [2], not even a computer science paper, offering a convincing treatment of a centuries-old riddle.
References
[1] Leslie Lamport: annotated publication list, here.
[2] Leslie Lamport: Buridan’s Principle, “to appear in Foundations of Physics“, dated 24 February 2012, available here.
