This is a very philosophical question; some writers will tell you that amazon means nothing, others that it mens little, and others that it is very important.

My guess is that a lot of pr-ordering on amazon helps a publisher judge how many books will actually be printed, since the print run can vary up tp the day a book goes to press. A lot of pre-0interest might affect advertising dollars, book tours, and the like as well.

Living for the amazon rankings is a bad plan...