Many people in the book trade are wont to make the sign of the cross whenever Amazon's name is mentioned. The online bookseller is credited with forcing publishers to slash their prices - and their profit margins.

But a recent spat between Amazon.com and publisher Macmillan might be an indication of a change in the balance of power.

Macmillan announced that it was changing the way it worked with Amazon when it comes to e-books. Amazon, it said, would become a sales 'agent'. The effect would be to allow Macmillan to better dictate prices. Amazon responded by removing the 'buy' button from all of Macmillan's products available on Amazon.com.

It was a nasty moment. Unusually, however, it's Amazon that has given way.

According to some in the publishing world, Amazon's position as the world's leading online book retailer has made it somewhat arrogant. To boost its own profits, it forces publishers to offer major discounts. Of course, Amazon isn't the only retail player flexing its muscle in this way. Supermarkets have been doing the same, and as publishers can't get high up the bestseller list without supermarket sales, they have had to go along.

It seems that Amazon has been doing the same with e-books, and that proved the last straw for Macmillan. Amazon wants e-books priced at $9.99, even for new, bestselling titles. Such prices not only encourage more book sales, they also boost sales of the Kindle. Publishers would be happier with something like $14.99. The fight was on.

Amazon's surrender to Macmillan surprised a lot of people, even if it was accompanied by a somewhat snippy remark to the effect that Macmillan has a "monopoly" on its own books. (Well, duh.)

But is it any coincidence that this has all come to pass just after the launch of Apple's iPad? I think not.

Macmillan is one of the five major publishers who had signed up for the iBookstore by the time of the recent iPad launch. Now the company has another major online retail outlet and (what is bound to become) another popular e-book reader platform.

There are plenty of e-book readers out there. But Amazon, with the Kindle, had done the best job of providing an integrated browsing, buying and reading platform. Now Apple has a better one. So it's not just the Kindle that is threatened by the iPad - it's Amazon's grip on the book market.