Unfinished Tolkien work to be published

This is interesting news: J.R.R. Tolkien's son Christopher has finished a book his father began but never completed, The Children of Hurin. It will be published in 2007. Given that the younger Tolkien has been working on this for the past 30 years, I wonder how much of the work is his father's and how much is his. Nevertheless, fans of Middle Earth will surely go nuts over another story about the elves and dwarves from LOTR. CNN story.