As most Gentoo users will have to compile packages sometime in their life(often the same or an updated version of the package) they might as well be introduced to ccache in the handbook. In chapter: http://www.gentoo.org/doc/en/handbook/handbook-x86.xml?part=1&chap=6#doc_chap1 the handbook mentions distcc. How about making a reference to the ccache guide: http://www.gentoo.org/doc/en/handbook/handbook-x86.xml?part=2&chap=3#doc_chap2 ? I think this "bug" is in all the different achitecture handbooks. Reproducible: Always Steps to Reproduce: 1. Go to http://www.gentoo.org/doc/en/handbook/handbook-x86.xml?part=1&chap=6#doc_chap1 and find that the book does not mention ccache.
distcc can considerably speed up the installation. Ccache however only speeds up rebuilding of certain packages and won't give you much advantage while installing Gentoo.
I think ccache should be mentioned in the handbook. Ccache is a cache and speeds up compiling only if it has stuff in the cache. So if we don't emerge ccache before emerge system, ccache will get the biggest boost the third time we will emerge something as the second time is the first for ccache. Ccache can in theory also speed up other emerges than just rebuilds if there are similar files.