Amazon's Kindle now ships with a built-in PDF reader and an extended battery life that reportedly keeps the device powered for up to 85 percent longer. The updates come just in time for the holiday season as Amazon tries to keep its e-reader on par with rival devices from Sony and Barns & Noble.

Amazon started shipping the latest generation of its popular Kindle e-reader on November 24.

"Kindle, already the #1 bestselling, most wished for, and most gifted product on all of, is now even better - with 85 percent more battery life and a built-in PDF reader," said Ian Freed, vice president, Amazon Kindle. "These two significant enhancements are available now."

Users will now be able to read personal or professional documents on their Kindle e-reader by emailing PDFs (portable document format) to their Kindle email address, or by transferring the documents to the device via a USB connection.

The firmware update will enable consumers to read for up to seven days with the wireless connection turned on (extended from four days).

Consumers who have previously purchased a Kindle e-reader from Amazon may also benefit from the firmware and PDF updates, without needing to manually update their devices. The free updates will automatically be delivered to compatible Kindle devices via Amazon's Whispernet service.

New Kindles purchased from the site will remain priced at $259.00.

More information about the Kindle update and for a list of Kindle e-readers that will benefit from the 2.3 firmware update can be found on Amazon's Kindle website: