TechCrunch, which is the site that broke the news about Amazon's tablet, seems to think another gadget is in the works:

Amazon just entered the tablet market this week with its Kindle Fire. But this time next year, it could be introducing its own smartphone. A research report put out this morning by Citi analysts Mark Mahaney and Kevin Chang states that an “Amazon smartphone may be coming next year.”

Based on supply-chain checks with hardware manufacturers in China, Citi believes that Amazon is jointly developing the smartphone with Foxconn, but that the phone itself will be manufactured by TMS (which produces the Kindle line).

This raises a lot of questions—would Amazon be using their own forked version of Android as a phone operating system? Would this still be a Kindle product, as in a media consumption device that also happens to make phone calls? With regard to Foxconn, did Jeff Bezos ever see Mike Daisey's most recent show?—but I'm sure there'll be no lack of speculation about this device in the year to come. It seems entirely plausible to me.