The Gentoo RepRap Overlay aims to add all the patches and tools you need
to run your ReRap under Gentoo Linux.

My RepRap is a RepStrap and its still very much under construction. This
overlay contains my tries on running all kinds of RepRap related software
on Gentoo Linux.

The ebuilds that don't have a keyword probably won't compile or have 
missing deps. The ~x86 ones compile, but there are some untested bin/library
combinations in them. Programming a (sanguino) RepRap motherboard and
basic interfacing with x11-apps/replicatorg-bin and x11-apps/reprap-bin
should be ok. 

The dev-embedded/arduino ebuild has sanguino and reprap USE flags that you
may use to patch the ebuilds /usr/share/arduino-XXXX dir with the needed 
libraries.