Whoops, I just asked the same question in another thread too. I'm taking the ferry from Bellingham, WA up to AK, and then driving the last little bit to Anchorage. Leaving middle of May now.
I actually called the Nissan dealer in Alaska, and they specifically said that the Nav system doesn't work up there. I didn't bother to ask whether they sell cars up there with it installed. My QX56 came with one, so I'm dying to have the nav functionality, especially because I'll be in a new place up there that I'm unfamiliar with.