Check out the videos hyperlinked in the article here; http://www.geek.com/articles/gadgets/nano-quadrotors-demonstrate-complex-swarm-behavior-2012021/
In the video where two of them build a tower, the “Matthew’s opinion” part is interesting:
“The important technology on display here is the accuracy of the quadrotors and the ability for them to work together. In their current small form the potential for them carrying objects is limited, but there’s nothing to say the quadrotors couldn’t be scaled up and made to carry much larger cargo.
The one limiting factor of the quadrotors is their battery life. But with such accurate movement it shouldn’t be difficult for them to navigate to and land on a charging pad. With teams of quadrotors working together recharges could be handled in such a way that there is always an active group of quadrotors working.”
Amazing.