I thought this was interesting. I heard the story talking about it on NPR. They told me to go to http://www.theworld.org for pictures. I had to take a look:
They claim that these bottles, stuffed with sand, are more durable than brick. The collection of these bottles reduce the amount of litter waste in the the local community and can be a profitable venture for those who collect. Great idea in recycling and reusable products. Bryan approves!