Google has already confirmed that they would be selling the Harry Potter eBooks later this year when Pottermore project launches.
Google would sell them through their Google eBookstore and consumers would be able to pay using Google Checkout platform.
Amazon has now indicated that they are in talks with the Harry Potter franchise to ensure that the same eBooks are also available on their Kindle platform.
The deal is not signed yet but Amazon would probably do their very best to ensure that Kindle owners would be able to buy the Potter eBooks from their store as well.