JavaCL is an Object-Oriented API that makes the C OpenCL API available to Java in a very natural way.
It hides away the complexity of cross-platform C bindings, has a clean OO design (with generics, Java enums, NIO buffers, fully typed exceptions...), provides high-level features (OpenGL-interop, array reductions) and comes with samples and demos.
For more info, please visit http://code.google.com/p/nativelibs4java/wiki/OpenCL.