Nasa purchased a 512 qubit D-Wave 2 quantum computer for $15 million. http://www.bbc.co.uk/news/science-environment-22554494
"D-Wave Systems has been focused on building machines that exploit a technique called quantum annealing - a way of distilling the optimal mathematical solutions from all the possibilities."
Apparently they work and are here to stay. I think inside 15 years this could be a real issue to sha-256 encryption. I have done some research into this and while at this time I dont feel this poises a threat, in the near future with optimizations and advances I think it very well could.
Anyone care to enlighten me further?