The US military are developing stretch tent looking solar powered canopies.  These tents would be popular at many of the green minded festivals if the technology goes commercial. Like the internet, mobile phones and the myriad other products this would be another example of military technology having great benefit for non-military users.

See the article in full on the link below.

http://www.army.mil/-news/2010/12/08/49138-army-evaluating-transportable-solar-powered-tents/