bordom in chickens

Hi and welcome to the forum.
Yes chickens can pluck each other's feathers out if they become bored or stressed.  My chickens are all rescue hens from battery farms and when they first are released they can be pretty much bald. 
I understand that it can be difficult for some people but honestly feel that chickens should have twice as much room as most people think they need.  They need room to scratch and stretch their wings as this helps to relieve their boredom and they also need space to get out of each other's way if there is any bullying.
In the meantime have you tried hanging greens (they particularly like dandelion leaves) for them to pick at in the run?  If they have enough space throwing a scattering of wheat on the floor for them to pick and scratch at can also take their minds of trying to eat each other! 
If they have pulled out feathers and the areas are sore they may then start to peck more as they are cannibals and do love the sight of blood.  You could buy some purple spray (go to your local pet shop or farm stores and explain the problem) which is an anti pecking spray that can contain an antibiotic to help them heal and to put them off pecking as it tastes horrible.
Anything else you want to know just ask and someone should be able to help.
Good luck.

Here's an article about behavioural enrichment for captive birds in zoos:
http://www.seaza.org/scientific_papers/behavioral_enrichment_for_birds_.htm

Obviously a lot of it doesn't apply to backyard chickens, but a lot does.  It talks about behaviour like aggression and feather-pecking as a result of boredom.  It also says that if a bird has been bored for a long time, it adapts to its boring environment and might resist changes, not wanting to interact with new 'toys'.