"Kurt Gödel---Separating Truth from Proof in Mathematics," by Keith Devlin. Science, 6 December 2002, pages 1899-1900.
The title refers to Gödel's Incompleteness Theorem, which Devlin explains in this article. He puts the theorem in historical context, discussing the axiomatization of mathematics in the 19th century and the Hilbert Program. There is also a brief summary of Gödel's life. He and Turing are the two mathematicians in the top 20 of Time magazine's list of most influential thinkers of the 20th century (published two years ago).
--- Mike Breen