A personal letter from Amazon.com CEO Jeff Bezos graced the front page of the online retailer Thursday, apologizing for the lack of Kindle electronic book readers and promising that production is being sped up.

Since the Kindle made its debut last November, the device has been in very short supply. Many buyers are waiting upwards of six weeks for their Kindle to arrive, and the situation hasn't improved much even after the holidays.

The Kindle is Amazon's first foray into manufacturing its own consumer electronics hardware, and some industry watchers speculate that the company wasn't prepared to deal with production problems when it put the device on sale and launched its wireless e-book store.

"We didn't expect the demand that actually materialized," Bezos wrote in his letter. "We sold out in the first 5.5 hours and have been scrambling to increase our manufacturing capability ever since." Bezos added that he expects the Kindle to be back in stock and shipping on the same day within the next few weeks.

Despite the production slowdowns, the Kindle has generally received favorable reviews from customers. The majority of reviews on Amazon are rated with 5-stars and most negative comments are about the general concept of electronic books rather than the actual device itself.

Amazon recently issued the first software update for the Kindle, version 1.0.4, but did not specify what changes it brings.