While I realize that this was discussed extensively in other threads I have not had the oportunity to weigh in on the matter in those threads so as I see it there is a profit vs compatibility issue here. If amazon supports epub they are opening themselves to competition from other electronic book stores, something no company would willingly do. While it is also true that savy costomers can simply translate from epub to the native format AZW with the aid of Calibre the average customer will not be savy enough to accomplish this on their own, hence the average customer is trapped in a prioprietary format. What will need to happen is something to get Amazon's attention and I fear that Rowling may not be enough.
This is my opinnion and it should be taken that way.