The ruins are inhabited by a scavenger that you can trade with or request repairs from. You can take his pre-War books and Nuka-Cola Quantum without penalty, but accessing his footlocker, food, purified water or other items counts as stealing. A number of frag mines are set up outside the house.
There is a random encounter nearby which may cause the death of the scavenger.
The scavenger ruins only appear in Fallout 3.