If you have volunteered for the local Republican Party you will probably be on the list. I had to call the organizers personally and ask if I could get tickets. They don't usually just know who all the Bush supporters are unless you have left your address and phone number with them at some time in the past. Now that they know me, I'm hoping that I will get notices of campaign events like this.
They should already have the addresses of all the registered Republicans in the state. An open rally with GB would be a great way for them to get more people, not "just" registered Republicans, to sign up as volunteers.
(I'll give the state organization the benefit of the doubt. They've gotten new leadership. I read a very bitter statement by the previous head of NHGOP recently, but I don't know what the circumstances were.)