In an open letter to customers today, Amazon's Jeff Bezos reported the availability of fresh shipments of its popular Kindle e-book reader, after having been in short supply since its November debut.

The Kindle device was officially launched in November 2007, but sold out in less than six hours due to a combination of high demand and major supply issues.

Amazon received harsh criticism after building up hype for Kindle's launch during the holiday season, then selling out in less than six hours with a very large back order. Officially released on November 21, 2007, Amazon promised the availability of more units on November 29, quickly apologizing for the miscommunication and lack of units available for purchase.

The Kindle features a 6-inch screen able to display 800 x 600 resolution, 256 MB internal memory, SD slot capable of holding up to a 4 GB memory stick, mini USB, keyboard cursor, full QWERTY keyboard, 3.5 mm headphone jack, and EV-DO. Furthermore, the device measures 4.9" x 7.5" x 0.7" and weighs 10.2 ounces. Up to 200 titles can be stored using the 256 MB of internal memory, with countless other titles available using an SD memory card.

Amazon did not publish the number of units it has available, but the Kindle still retails for $399 with free two-day shipping.

There are few other options available in the e-book market today, though Kindle is competing with the Sony Reader Digital Book PRS-505. This reader also features a 6-inch display, but does not have a QWERTY keyboard or wireless Internet access. Nonetheless, it does costs less with prices starting at $299. The Sony product measures 6.9" x 4.8" x 0.3" and weighs 9 ounces, and has 170 PPI resolution, with the ability to store up to 160 books at any given time.

Philips Electronics launched its iRex iLiad in 2006, but the $800 price tag quickly made interested consumers lose interest in the device.