"Starting February 28, the first half of Need You Now is available for 99 cents from all major e-book retailers. In mid April, the second half of the e-book, as well as the full e-book and the physical trade paperback will be available. The second half of the e-book will have a list price of $10.99, and the complete e-book as well as the trade paperback will have list prices of $15.99."
Read more about Nelson's interesting move here.
I'm not sure it's been tried before. It will be interesting to see if it pays off.