I completely agree that Julia and SciPy are complementary rather than competing. I've attended the SciPy conference for several years and it's great – I love the Python and SciPy communities. It's definitely crucial to both be able to easily call existing C and Fortran libraries and write code in the high-level language that's as fast as it would have been in C. You don't want to reimplement things like BLAS, LAPACK and FFTW – but you do want to be able to implement new libraries without coding in Fortran or C, and more importantly, be able to write them in a very generic, reusable fashion.
I completely agree that Julia and SciPy are complementary rather than competing. I've attended the SciPy conference for several years and it's great – I love the Python and SciPy communities. It's definitely crucial to both be able to easily call existing C and Fortran libraries and write code in the high-level language that's as fast as it would have been in C. You don't want to reimplement things like BLAS, LAPACK and FFTW – but you do want to be able to implement new libraries without coding in Fortran or C, and more importantly, be able to write them in a very generic, reusable fashion.