I don't think that variadic templates should be disabled for gcc prior to 4.7, even with this problem, since the implementation is sufficient for many use cases. I'm not a Boost developer, but it makes sense that this belongs with other workarounds. The GCC C++11 support table claims that 4.4 supports variadic templates. GCC treated the problem as a bug, whose report claims it is fixed in 4.7.0. That seems appropriate for a workaround. Since at least 2 libraries already need this workaround, I think it's reasonable to replace the library-specific macros with a general workaround macro.
OK, I've added a new config macro - BOOST_NO_CXX11_FIXED_LENGTH_VARIADIC_TEMPLATE_EXPANSION_PACKS - to develop. Test case failed for Intel-win as well as GCC, so apparently it's not just a GCC issue after all.
Whatever the final decision, I would eventually like to know how to patch my copy of 1.56.0, including your fix for gcc.hpp.
Grab the changed files from Github? John.