William Scullin’s talk from PyCon 2011: Python for high performance computing.
At least in our shop [Argonne National Laboratory] we have three accepted languages for scientific computing. In this order they are C/C++, Fortran in all its dialects, and Python. You’ll notice the absolute and total lack of Ruby, Perl, Java.
If you’re interested in Python and HPC, check out SciPyTip.