Basically, Jeff Cooper (a legend in the rifle world), came up with a general purpose rifle concept. The idea is to have a light weight rifle that's easy to carry, bolt action, accurate, and can quickly and humanely kill anything within sight. The concept also included a forward mounted "extended eye relief" scope.
These scout scopes are usually only magnified 2-4x, and works kind of like an early incarnation of the red dot site. You keep both eyes open, put the rifle to your shoulder, and you're almost immediately on target. With both eyes open you keep your peripheral vision, you can track moving targets quicker. It's very fast, that's the idea.
(Ruger Gunsite Scout with Scout Scope)
Probably the most true-to-concept rifle mass produced is the Ruger Gunsite Scout. Gunsite is the organization founded by Jeff Cooper, they collaborated with Ruger to make a rifle to fit Cooper's specifications. Gunsite held a show and tell with the rifle and dozens of Rifle reviewers showed up. The videos are very cool and describe the rifle and the concept very well.
Here are the videos put out by Gun Talk TV:
A lot of people think that the Scout Rifle is a pointless idea, that it compromises too much. To be decent at a lot of things means it's isn't really good at anything. It's not a sniper rifle, it's not a hunting rifle, it's always somewhere in the middle.
However, for people like me that think the idea of a 'general purpose' rifle is a good one, the Ruger GSS or similar scout platforms are definitely worth a look. And yes, this would make a good Bug Out rifle, or one **** of a zombie killer.