Yesterday Nanosolar announced it has started to sell cheap solar panels at a materials cost of roughly $1/W and a finished panel cost of ~$2/W: http://www.reuters.com/article/technologyNews/idUSN1846022020071218. As a reference point, coal powered electricity is about $1/W when considering the fully burdened cost of the plant and operations. When a new technology is within a factor of two of an old, heavily invested technology, I get excited. This is getting interesting.
Nanosolar was founded in 2002 and has plants in San Jose, CA and another near Berlin, Germany. They received $20M from Mohr Davidow Ventures. Other investors include Sergey Brin and Larry Page.
More articles on Nanosolar: http://www.nanosolar.com/articles.htm. Thanks to Will Whitted for directing me to Nanosolar.