Amazon practically invented the e-book market with their first Kindle reader back in 2007. Since then they've been refining the technology, adding touch-based screens and better resolution. The Kindle Paperwhite, Amazon's e-reader with a frontlight, was recently released to glowing reviews.
The newest Kindle has been so popular that the ship date has been slipping. Last week Amazon predicted a ship date of October 22nd, and today that date has been pushed back to sometime in November. According to Digitimes, the delay could be caused by issues in the supply chain, but the fact that the date has been slipping indicates that demand for the device is extremely high and is expected to reach a few million in 2012.
Interestingly, the Kindle Fire HD is not experiencing a backlog. It's unclear whether there are simply no supply chain issues with the tablet or if the demand simply isn't as high.