Shared-memory Parallelism for Fortran, C and C++
The OpenMP Application Program Interface (API) supports multi-platform shared-memory parallel programming in C/C++ and Fortran on all architectures, including Unix platforms and Windows platforms. Jointly defined by a group of major computer hardware and software vendors including The Portland Group, OpenMP is a portable, scalable model that gives shared- memory parallel programmers a simple and flexible interface for developing parallel applications for platforms ranging from the desktop to the supercomputer.
(NEW) Watch the OpenMP 3.0 and Task Parallelization video (time: 4:18)
Some useful information on the OpenMP initiative.