Amazon.com's press invite sent out Friday did not mention what the event is on Sept. 28 leading to speculations that the online shopping website will launch its Android tablet PC on Wednesday.

The invitation that simply says, "Please join us for an Amazon.com press conference" plus the time, date and location was e-mailed to reporters. Amazon did not want to elaborate on the event.

But analyst Jack Gold of J. Gold Associates said it was the right time for Amazon.com to launch its tablet ahead of the unveiling of Apple's iPhone 5 smartphone on Oct. 5.

"Amazon has to get on the ball with the tablet launch before Apple comes along and steals all its thunder," said Gold, according to Computerworld.com. "Once the new iPhone is launched, the press will not talk about anything else for days or weeks," he added.

Aside from an early launch date, Amazon is reportedly selling its tablet for more than half the price of the Apple version, which was priced at $499. The attractive price may well be a good marketing ploy but technology researcher Gartner said it's unlikely to beat the Apple iPad's 70 percent share of the tablet market overnight.

The still unnamed Amazon tablet features a full-color 7-inch touchscreen and resembles Research in Motion's BlackBerry PlayBook, online news site TechCrunch reported on Sept. 2. It will also be back-lit unlike the e-ink Kindle e-readers.