I think right now there are states that draw 20%+ of their electricity off of wind. Kansas or Iowa, I'm pretty sure.
Texas is into it heavy. The funny thing about the reliability argument, at least in Texas, it turns out that coastal wind is more reliable than coal and gas during summer peaks. There's less maintenance and fewer operating caps (water temperature can affect cooling and steam generation), and one thing that is pretty reliable is on-shore breezes being generated by the heating of the land on peak demand days.