Well, As OpenGL is for Graphics only it has no use in Audio processing at all, it is good for fast screen operations, realtime oscilloscopes etc
You should edit your title to say OpenCL to get a better response from other audio users who are watching this area though as the question has popped up a few times.
OpenCL is a bit like how a CPU uses multithreading but on the graphics cards stream processors (of which there are many) instead. Most audio processing e.g. effect plugins from what I understand do not gain much benefit from parallel processing, which is what OpenCL is all about.
But you never know, some very creative people out there will be trying all sorts of new things with it for lots of different applications.