I don't consider CUDA in the mix because it's designed specifically for GPUs. But, yes, OpenMP has much more traction in the HPC community, because it was designed by and for them. Its task parallelism, though, is rather ugly. I don't know what Cilk's data parallel abstractions look like, but I suspect they're better than OpenMP's task parallel abstractions. (Just because, well, I think OpenMP's are that bad.)

But, fundamentally, OpenMP is not integrated into the language. It's tacked onto the language through pragmas. I think that was a hack, not a long-term solution. And I say this as someone who did the exact same hack: http://people.cs.vt.edu/~scschnei/papers/scott_dissertation....