Amazon Kindle Amazon has posted a preview of the future of e-books, its Amazon Kindle e-reader app for the Apple iPad. Amazon is teaming its e-book format with the most anticipated tablet device we've seen so far. Altogether, that will almost certainly make the iPad the world's top e-reader.

If this all works out - and where Apple and mobile apps are concerned, you can never be too sure - this could make the iPad attractive to everyone who owns and Kindle but wishes they could do more with it. It also makes Apple interesting to people, like me, who want an e-reader but never seriously considered an iPad.

A rocky marriage of convenience

But, sadly, I'm already wondering whether this marriage of convenience can be saved.

First, it's not clear Apple whether has even approved Amazon's Kindle app for iPad and its associated e-bookstore. It is not impossible that Amazon hasn't received approval and is, essentially, playing chicken with Apple. Or maybe all is peaceful, the deal has been done, and Apple has suddenly learned how to play well with others.

Apple's strong preference to have tight control over applications and content on its mobile devices is what makes the idea of a Kindle app and competing iPad book stores seem so strange. Barnes & Noble has said it plans a Nook iPad app and store too.

At some point, Amazon and Barnes & Noble are almost certain to chafe under Apple's reins. It's not clear whether either bookseller really wants to be in the hardware business, but it wouldn't be wise to get out of it any time soon.

Compatibility - but for how long?

Today, it makes sense, especially for Apple, to make the iPad compatible with the Kindle and Nook, but should Amazon and/or Barnes & Noble get out of the hardware business, I can imagine compatibility could disappear fairly quickly, leaving Apple's own iBooks store as the only option for the iPad.

I don't think Apple sees a reason why Amazon or Barnes & Noble should be allowed to live as e-book reseller, when Apple does so well with other content all by itself.

But there is a good reason for Apple to allow competition, and it presents itself in the form of the US Department of Justice, which might step in on the side of Amazon and Barnes & Noble should Apple behave too aggressively.

E-book users should hope that Apple will understand the differences between its music and apps stores and selling e-books online, as well as accept that a separate category of e-reader hardware will exist, mostly at lower prices than the iPad.

We can hope all that, but Apple getting along with sometime competitors is an uncommon thing.

Today, this co-operation looks like a shotgun wedding. Apple and the booksellers each have something the other needs. Apple needs content and e-book customers, while Amazon and Barnes & Noble benefit from Apple's hot new platform.

We'll have to wait and see how long this lasts.

See also:

Survey: iPad vs Kindle to be tight battle

Apple iPad news spotlight

E-book reader reviews

Apple iPad review

Amazon Kindle review

Barnes & Noble Nook review

PC World