Online retail giant Amazon is planning a big event on Sept. 6, summoning the media but staying mum on details. "Please join us for an Amazon Press Conference," reads the full text of the invite sent out to the media. The event will take place at the Barker Hangar in Santa Monica, California, where the timing seems perfect for a new line of Kindles, including a new Kindle Fire tablet.

At the event Amazon hosted a year ago, the retail giant unveiled a whole Kindle lineup, including the Kindle Fire, which proved to be exactly what everyone had expected: a 7-inch Android tablet focused on media consumption and priced below Apple's market-leading iPad.

Looking ahead, September seems quite a busy month: Nokia and Motorola releases are expected on Sept. 5, the Amazon event takes place on Sept. 6, and Apple is expected to unveil its next-generation iPhone, along with a cheaper, smaller iPad, on Sept. 12. It would make sense for Amazon to unleash its new Kindle Fire tablet on Sept. 5, ahead of the rumored iPad Mini launch a week later.

The new Kindle Fire, however, will now enter a much more crowded and competitive market for 7-inch tablets. Even if Apple fails to jump in with a smaller iPad, the blockbuster Google Nexus 7 tablet, which runs the latest version of Android on more powerful hardware than the Kindle Fire and sports the same $199 price tag, is a powerful competitor.

An report from All Things D last month, citing sources familiar with Amazon's plans, claimed that the new Kindle Fire would feature a built-in camera, a much-improved display with 1280 x 800 pixel resolution, and an entirely new width-to-height ratio.

"The new tablet will be lighter and thinner than the original," ATD wrote on July 8.

Amazon's announcement also follows the biggest quarter in tablet sales history, as tablets set a new sales record for the April-to-June quarter. According to ABI Research, overall media tablet sales hit a whopping 25 million units in the quarter, marking a 77 percent year-over-year growth of the market.

"New vendors and products are entering the fray during the second half of the year, including tablets from Google and Microsoft," said the research firm. "ABI Research expects the new products to impact shares - both positively from Google Nexus 7 and negatively from Microsoft's Surface tablets - of Google's Android OS, used on most tablet models." According to ABI Research, Amazon comes in third in tablet sales, trailing behind Apple and Samsung.