I'd argue that compared to OpenMP and CUDA, Cilk has very little traction. My frame of reference is the current set of HPC platforms, though. We had one customer who wanted to build Cilk, and it was really just for R&D, not production.
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....
And re: data parallelism, I don't see that anyone has made a terribly popular implementations. The niche languages like UPC, CAF, and HPF all seem to have withered on the vine. So far, the only thing people seem to buy into is that openmp-based task parallelism is easier than managing threads by yourself.