A variety of reasons really. In no particular order: - Still has good math support, rapid development - Better OOP support - More libraries -- everything from web development to scientific computing to GUIs to databasing - More reliable, less buggy - Better development tools -- code completion, testing, coverage, profiling, etc - Free. Therefore can more easily be run on clusters without licensing issues or using the MATLAB MCR

I don't see any friction, except if one needed to port old code. It seems that a lot of people are moving toward SciPy/NumPy these days.