As of earlier this month, Intel landed Cilk Plus multi-threading support in GCC ahead of next year's 4.9 release. Cilk Plus aims to make parallel programming easier. With the initial GCC support there was the new Cilk Plus open-source run-time library added plus the cilk_spawn and cilk_sync keywords. The cilk_spawn keyword allows calling a function that can execute in parallel with the caller while cilk_sync ensures all child function calls spawned have finished before proceeding.
The third and only other programming keyword to Cilk Plus is cilk_for, which turns for-loops into parallel for-loops to execute simultaneously across all available CPU cores. Support for cilk_for is Intel's latest GCC contribution.
As of Friday there's a Cilk_for patch for C and C++ sitting on the GCC mailing list. This final bit of Cilk Plus enablement will hopefully be in great shape for the GCC 4.9 compiler update in 2014.