I would say that statistic and probability theory are probably the most important thing to learn for anyone that analyses data, yet most programmers are clueless and statistics isn't that popular in CS programs (at least the one I had or have heard of).
If you come anywhere near Machine Learning, statistics becomes extremely important. Statistics, Calculus and Linear Algebra are definitely prerequisites for even a rudimentary understanding of the algorithms. You are dealing with inherently probabilistic problems, and optimizing functions on many dimensional spaces. It's pretty much all math, actually.
