Ah, yes-- I certainly wouldn't mind a sequel of some sort. I actually did some wikipedia-ing and found out that.... Moribito: Guardian of the Spirit (精霊の守り人, Seirei no Moribito?) is the first in the ten volume Guardian (守り人, Moribito?) series of Japanese fantasy novels, written by Nahoko Uehashi.
So if we do have a sequel coming up, the writers have 9 other stories to choose from! =DD
edit-- Ah, wait; It's a continuing series. So if they do make a sequel, they'll make Yami no Moribito first.