By Iain Mackenzie
Newsbeat US reporter
Amazon's original Kindle digital book reader was launched in 2007
Online retailer Amazon has launched the new version of its electronic book reader, Kindle.
Kindle 2 is thinner, slightly lighter and has a longer battery life than the original version that went on sale in November 2007.
The company says its new model has seven times more memory, enabling it to hold up to 1,500 titles.
The increased storage capacity brings Kindle closer to the idea of being an iPod for books.
Amazon also announced plans to make all books available for download in electronic form.
Amazon Founder and chief executive Jeff Bezos said: "Our vision is every book, ever printed in any language, all available in less than 60 seconds."
He revealed that, where a Kindle version of a book is available, it accounts for 10% of Amazon sales.
However, there was no news from Amazon regarding Kindle availability outside the United States.
Steven Kessel, Amazon's Senior Vice President of Digital Media at Amazon told BBC News: "We have lots of inbound requests from customers around the world.
"We have no announcements for them today, but we continue to get those requests."
In the US, Kindle users can download e-books over the wireless 3G network, without paying data charges or monthly subscriptions.
Amazon insists that Kindle has proved highly popular during the 14 months that it has been available.
Devices sold out soon after the launch of Kindle 1 and again before Christmas 2008.
The company refuses to provide exact figures, however some analysts put the number sold at around 250,000.
The re-vamped Kindle 2 adds a five-way joypad for navigating around pages.
Battery life is said to be 25% better than the previous version, giving two weeks reading between charges.
Author Stephen King was at the Kindle 2 launch in New York
Kindle 2's display is upgraded from four shades of grey to 16, making pictures look more realistic.
Critics of Kindle point to its high price of $359 (£244), claiming it is an expensive luxury compared to the price of paper books.
E-book downloads are cheaper than their physical counterparts, with most best-sellers retailing for around $9.99 (£6.70).
Many new e-books are copy-protected using Digital Rights Management (DRM) technology.
Similar systems are used by music retailers, such as Apple's iTunes, to prevent customers playing their songs on other manufacturers' devices.
Amazon's .AZW file format can currently only be viewed on Kindle devices.
Several other electronics companies have launched portable e-book readers, including the Sony and iRex.