Amazon’s syncing service, Whispersync works in tandem with Whispernet, a free cellular-based network piggybacking off Sprint that 3G Kindle users can connect to for free. This is the first time that Whispersync  used mainly for bookmarking Amazon e-books. Allowing readers to pick up where they left off reading, even when switching between different Kindle devices and platforms.

According to sources, Whispersync is the secret sauce in the company’s plan to dominate the tablet industry.

It acts as a large-scale distribution mechanism following the syncing and uploading of textbooks in Amazon’s new textbook rental service.

Amazon’s Kindle VP Dave Limp noted that the rental service will make available of 230,000 textbooks for students on Kindles at discounts of up to 80%, which can last up to 360 days.

They are extending the Whispersync technology so that people can keep, access all the notes and highlighted contents in the Amazon cloud.  There will be no need to hurry since the notes will be available anytime one want to access it.

The effort begins with books, but it could end with music and video.  Possibly, in an email on an Amazon tablet, which could last up to 90 days?  To date, Amazon neither confirms the existence of their tablet nor denies it.

Whispersync will be the key to Amazon’s tablet plans and to represent the company’s ultimate weapon against the tablet space’s Apple.

Forrester analyst Frank Gillett says he believes that Amazon is gunning for iPad.

If the dots are all connected, Amazon is gearing toward the Apple’s iCloud.  The effort will produce some new services from Amazon, like email, since the company moving toward helping consumers to manage not only the commercial content that it sells, but also personal content.

The tablet rumored to ship in a nine-inch form factor. Whispersync essentially turns the future tablet–or a Kindle–into a WiFi-free cell device that uses Cloud Drive in sharing and syncing large volumes of rich media, which includes books, music, photos and video.

This feature is unique and would appeal to numerous people since all they have to do is to look at the gadget and they got a signal.  It is simplicity at its best.

Amazon’s tablet may not defeat Apple’s tablet in terms of cost. Priced effectively, the combination of the Amazon Marketplace, Cloud Drive, and cell-based syncing service will likely boom with media users.

Whispersync-enabled Android tablet is going to be available by mid-October.