The PDF support is an important feature given the popularity of the format among businesses. Amazon's major rivals, Sony and Barnes & Noble, offer PDF support in their e-readers, the Reader and Nook, respectively.
Before the firmware upgrade released Tuesday, Kindle owners had to convert PDF documents downloaded from a PC into the e-reader's proprietary format. Native support for the format should reduce the hassle in reading such documents, which still have to downloaded to the Kindle through its USB connection.
Amazon has had a PDF reader in the larger Kindle DX, which is more geared toward business users than the basic Kindle with a six-inch display. However, neither device supports ePub, an open e-book standard by the International Digital Publishing Forum.
Not having ePub support means the Kindle and Kindle DX cannot read the half-million free, non-copyrighted library books available through Google Books. Many analysts believe ePub support is an advantage for the competitors from Sony and Barnes & Noble.
Besides adding a PDF reader, the Kindle firmware update also extends the battery life of the device to a week from four days with the wireless capability turned on. With wireless turned off, the Kindle can go up to two weeks without a charge.
The wireless capability is used in automatically delivering firmware updates and for buying and downloading e-books from Amazon. Barnes & Noble's Nook and some models of Sony Readers have the same capability for accessing the vendors' online stores.
Amazon released its latest update as competition heats up in the e-reader market. While Amazon is the current leader, Barnes & Noble appears to be doing well with the Nook, which debuted last month. According to Barnes & Noble's Web site, the device is sold out, and people pre-ordering a Nook today will have to wait until after the holidays. Barnes & Noble expects to resume shipping the device Jan. 4.
E-readers have proven popular among business travelers and avid readers. Forrester Research predicts e-reader sales this year will reach 3 million units, with 30% of the purchases occurring during the holiday season. E-reader sales next year could exceed 6 million units, according to Forrester.