Very serious. A solar thermal plant pumping out electricity at 5 cents/kWh (or less!?!) would be pretty amazing. This advance in efficiency is coming through a redesign of the mirrors with new material on both the reflective surface and the substrate.
From the link:
Google announced last year that they were working on new technology that would make solar thermal energy cheaper than coal. Just a few months later, they have a prototype and expect a product to be ready in as little as a year.
The prototype is being internally tested before more rigorous external testing, but two solar companies, BrightSource and eSolar, are already interested in the technology. Google is a major investor in both companies and has said if the prototype works, the companies would use the technology.