They have now opted out of whatever the city offered. They have chosen to locate in Altoona, Iowa, a town near Des Moines. Having been a reporter for the Audubon, Iowa newspaper, I'm guessing that one main reason for this location choice is because that area of Iowa have been developing wind energy and erecting several wind turbine farms around the area. Nebraska is lacking in wind energy opportunities for companies wanting to "go green".
http://www.kearneyhub.com/news/local/kearney-was-finalist-for-facebook-s-billion-data-resource-center/article_ecb3db06-ac33-11e2-84d5-0019bb2963f4.html
http://www.kearneyhub.com/news/local/kearney-proud-to-be-only-other-finalist-for-billion-facebook/article_5e6f4e9c-ac61-11e2-b21e-0019bb2963f4.html