It is coming out the summer after SHOT, at least it has been the last three SHOT Shows now. So far as I can tell the hammer is much like shot show, except swap one of the "Os" for an "i." Lets hope it isn't plagued with teething problems when it hits the market. :/
For what it is worth, I am awaiting the Hammer with great anticipation too, I'm just a bit dismayed at how Umarex seems to have no compunction about allowing their dealers to sell pre-orders on a product which they clearly have no capability to deliver in a timely fashion. There is fashionably late, and then there is just stupidly late.....