There exist C++ libraries such as Eigen or Boost::uBlas that implement matrix types and computations.
There also exist libraries such as LAPACK, Goto-BLAS, OpenBLAS and ATLAS that implement highly optimized dense matrix computations over floating-point types.
I was wondering whether some C++ libraries, perhaps through specialization, call OpenBLAS for the types supported by OpenBLAS. It would seem the best of both worlds.