Gentoo Linux is a Linux distribution built almost entirely from source. It has an advanced package management system called Portage. Some consider Gentoo a meta-distribution because of the incredibly flexible installation process.
One of the goals for Gentoo Linux 1.4 is the addition of the GRP--the Gentoo Reference Platform--which will allow users to install precompiled packages built to certain baselines specifications. This may be an attempt to appease naysayers; some believe that Gentoo users spend too much time compiling and recompiling common packages.