I recently installed gcc 4.8.2 and boost 1.55.0 on CentOS 6.4 to take advantage of the improved support for C++-11. It was painful to do manually so I automated the process with this script: http://projects.joelinoff.com/gcc-4.8.2/bld.sh. Hopefully this will make it easier for folks that want to experiment with the latest version of the GNU C++ compiler.
If you are interested in a more recent version, I recently added a post that provides a script to install gcc-4.8.3 and boost 1.55.0.