Kindle DX

On May 6, 2009, Amazon announced the Kindle DX, which retails for $489. It is the first Kindle model with an accelerometer, automatically rotating pages between landscape and portrait orientations if the device is turned on its side, unless automatic rotation is disabled by the user. It is slightly over 1⁄3 inch (about 8.5 mm) thick, has a 4 GB (3.3 GB user-accessible) storage capacity, holding approximately 3500 non-illustrated e-books, a 9.7 inch (24.6 cm) display with 1200 x 824 pixel resolution, and a battery life of up to one week while using wireless or two weeks offline. The DX adds support for PDF files natively, built-in stereo speakers and 1xRTT wireless technology as a fallback option for when EVDO connectivity is not available. Like the Kindle 2, it does not have an SD memory card slot. The model was released on June 10, 2009. more about Kindle DX Wireless Reading Device (9.7" Display, Global Wireless, Latest Generation) click here

Kindle 2 international version

On October 7, 2009, Amazon announced an international version of the Kindle 2 that works in over 100 countries. It became available October 19, 2009. The international Kindle 2 is physically very similar to the U.S.-only model although it uses a different mobile network standard. The original Kindle 2 uses the Sprint network while the international version uses AT&T's U.S. mobile network and roams on 3G, EDGE and GPRS on GSM networks in other countries  On October 22, Amazon lowered the price on the international version to $259 from $279 and ceased selling new versions of the U.S.-only model.

Kindle Wireless Reading Device (6" Display, Global Wireless, Latest Generation)

The Kindle International Wireless version has restricted access to the experimental web browser. In most countries, Amazon restricts Kindle owners from accessing any web content apart from Amazon's e-book store (to view and purchase books and magazine subscriptions) and the English Wikipedia.

Similar to an iPod/iPhone, the Kindle 2 does not have a removable battery. If the battery fails on a Kindle 2, the whole unit must be sent to Amazon for repair.

Kindle 2

On February 10, 2009, Amazon announced the Kindle 2. It became available for purchase on February 23, 2009. The Kindle 2 features a 16-level grayscale display, improved battery life, 20 percent faster page-refreshing, a text-to-speech option to read the text aloud, and overall thickness reduction from 0.8 to 0.36 inches (9.1mm).

The Kindle 2 has 2GB of internal memory of which 1.4GB is user-accessible. Amazon estimates that the Kindle 2 will hold about 1500 non-illustrated books. Unlike the Kindle First Generation, Kindle 2 does not have a slot for SD memory cards. To promote the new Kindle, author Stephen King made UR, his then-new novella, available exclusively through the Kindle Store. On October 22, 2009, Amazon stopped selling the original Kindle 2 in favor of the international version it had introduced earlier in the month. see Kindle Wireless Reading Device (6" Display, Global Wireless, Latest Generation)

According to an early review by iFixIt, the Kindle 2 features a Freescale 532MHz, ARM-11 90 nm processor, 32MB main memory, 2GB moviNAND flash storage and a 3.7V 1530mAh lithium polymer battery. On November 24, 2009, Amazon released a firmware update for the Kindle 2 that it said increases battery life by 85% and introduces native PDF support. There is concern about the specific hardware choices made for the device.[23] For example, the Kindle 2 lacks the memory expansion slot which was part of the original Kindle, which not only affects the potential number of e-books which can be stored on the device, but also removes potential capabilities to import e-books onto the device via memory card.

There are concerns that the Kindle 2's contrast in small text is poor compared to the original Kindle. Side-by-side comparisons show slight differences attributable to factors such as slightly darker background and different fonts on the two devices. Some Kindle 2 users have reverted back to the original Kindle due to this issue.

The Kindle 2 was criticized for its high original retail price of US$359, compared to the $185.49 it allegedly costs to manufacture. On July 8, 2009, Amazon reduced the price of the Kindle 2 to $299. On October 7, 2009, Amazon further reduced the price of the Kindle 2 to $259.

Original Kindle

Amazon released the Kindle First Generation on November 19, 2007, and it sold out in five and a half hours. The device remained out of stock for five months until late April 2008.

The Kindle First Generation device features a 6 inch (diagonal) 4-level grayscale display and retailed for US$399. Amazon subsequently lowered the price to $359. The 250MB of internal memory in the Amazon Kindle First Generation can hold approximately 200 non-illustrated titles, and the memory is expandable with an SD memory card. This model is no longer available as a new item, because the Kindle 2 replaced the original version.

On the Kindle First Generation, the Whispernet only works in the United States, but content can be downloaded from Amazon over the Internet. Amazon did not sell the Kindle First Generation outside the United States. Plans for a launch in the UK and other European countries were delayed by problems with signing up suitable wireless network operators. Another hardware decision which has been questioned is the non-availability of WiFi functionality on the Kindle. Instead, the device relies on Sprint's EVDO, AT&T's 3G network, or 1xRTT data services for Internet access, which, critics argue, does provide a large amount of geographical coverage, but also drives the price of the device up considerably.
more about Kindle: Amazon's Original Wireless Reading Device (1st generation) click here