While being reported that more publishers are pushing amazon to drop the 9.99 price point for ebooks gizmodo Amazon still has a major advantage and apple has an uphill battle on the ebook front.
People out of habit go to amazon for their books needs. When you think of books, you think of amazon and so the kindle has a great resource that apple does not. While they've signed many of the major publishers, that may not instantly translate into massive ebook sales.
This makes no sense, how is this an advantage for Kindle over iPad? People out of habit go to Amazon to buy PHYSICAL copies, not ebooks. Kindle owners go to Amazon because it's built right in, where else would they go? Same for iPad, they'll go to iBooks if it's built in. Neither has an advantage over it.
How about this instead, people buy applications, music, videos through iTunes all the time, why would they want to go to Amazon web site through Safari to buy ebooks when they can just go to iTunes on their iPad or iPhone? Apple already have a large number of iTunes paying customers who might just rather buy books through iTunes than Amazon.