The graphite and display overhaul that Amazon gave its Kindle DX earlier in the month has now been applied to its third generation 6-inch model. The new Kindle will be available with 3G and Wi-Fi or Wi-Fi only, is 15 percent lighter and 21 percent smaller than its predecessor but still retains the 6-inch display and now comes with double the storage capacity.

The 6-inch Kindle will now be available in two options, one with 3G and Wi-Fi and one with Wi-Fi only. The 3G model weighs 8.7 ounces and retains the pencil-like thinness of the previous generation. The Wi-Fi only model is similarly 1/3 of an inch thin but is marginally lighter at just 8.5 ounces. Either way, both models come in lighter than a paperback and thinner than a magazine.

Both have a smaller 7.5 x 4.8 x 0.335 inch body but retain the 6-inch reading area, which has now received the same e-Ink improvements recently given to the DX. As well as 50 percent better contrast, the company has given its proprietary waveform and font technology a bit of a tune-up, which it says results in significantly faster page turns and crisper fonts. And, like the DX, the new Kindles are offered in a graphite option.

Storage capacity has been improved as well, the new devices now capable of storing 3,500 eBooks and the inclusion of Whispersync technology lets users read an eBook across numerous devices and keep track of progress on all of them.

The U.S. Kindle Store now has over 630,000 titles, with the vast majority of those coming in at under US$10. There are also more than 1.8 million out-of-copyright eBooks available for free download and any books purchased from the Kindle Store are automatically backed up online and available for subsequent free download in the event of accidental deletion. Kindle users also benefit from wireless coverage in over 100 countries and territories.

The new models claim up to a month's battery with the wireless off or up to 10 days with it switched on, but readers are likely to experience something in between as they toggle between online and offline modes. There's an improved PDF reader with new dictionary look-up, notes and highlights, and support for password protected documents. A WebKit browser is included with a new article mode that simplifies web pages to appear as just text for easier reading on the device and built-in Twitter and Facebook integration gives users the option to share favorite quotes or passages with network contacts.

The new models are available now for pre-order with an expected shipping date of August 27. The 3G and WiFi model is priced at US$189 and the WiFi only Kindle will cost US$139. Amazon says that it's also arranged for free wireless access at AT&T Wi-Fi hotspots across the U.S. for shopping and downloading content with no AT&T registration, sign-in or password required.

Kindle lovers from the UK might also be interested to learn that the new devices are now available for pre-order on dedicated Amazon UK pages. Details of the WiFi only model can be viewed here and the 3G and WiFi Kindle here. A new UK Kindle Store is also expected to open its virtual doors on August 27.