I saw some at a Walmart DC in Ohio.. Walmart can and does push whole industries. I think I saw an article about Walmart now using them entirly in a DC somewhere.

I believe that fuel cells WILL be here to stay, and will eventually dominate the market. The advantages outweigh the disadvantages, though currently the costs are limiting fuel cell use.
As stated above give the industry a few years and I believe that fuel cells will be the norm.