SciPy is used in various projects, including even the digital humanities project SPuDisc, where a Python/SciPy-based program learns to model and recognize emotional expressions in text.
NumPy and SciPy extend the Python programming language with fast numerical computing capabilities. They contain many building blocks for scientific applications, such as linear algebra, statistical tests, optimization and random number generation. Add-on packages further extend SciPy with plotting (Matplotlib), interactive use and code sharing via the web (IPython) statistical modeling (statsmodels), machine learning (scikit-learn) and distributed computing (various packages).
Python is on its way to becoming the lingua franca of scientific computing. It's an easy-to-learn language that can be used in scripts or interactively. Together with SciPy and associated tools, it is the prime open source alternative to Matlab.