A curated app store (and note it is an *APP* store, not an *Android* app store--nowhere has Amazon said it will be limited to android) fills a market gap *and* it is a logical extension of Amazon's boxed software sales as well as their music, video, and ebook stores.
Note too, that of all the three, only the ebook store bears the Kindle name.
In addition, Kindle runs apps of its own but since it runs Linux, not Android, putting the Kindle name on a hypothetical Amazon Android tablet would risk complicating the Kindle marketting storyline especially if people expect the "Android-Kindle" apps to run on the K2/K3.
Finally, there is no shortage of Android tablets on the market, with more coming every day. A store lets Amazon, at a minimum, milk the sub-Honeycomb tablet market pretty much at will. They may even get enough visibility that way to be able to challenge Google's market on Honeycomb tablets.
If they did an Android 3.0 they would have to license the Google apps from Google (who may not be happy with Amazon for competing with their market) or be stuck with a 2.x tablet in what will soon be a 3.x Android market.
One other possibility: Amazon will be very likely hosting PC downloads and (maybe) WebOS, WP7, and/or Playbook apps.
A much less likely (but not impossible) scenario would be for them to offer up apps (plus music, video, and ebooks) for jailbroken iOS gadgets if Apple evicts them in June. Not sure what kind of legal warfare might ensue if Amazon offered up the actual tools for jailbraking but it is not clear that they would lose, given existing "fair use" type rulings on jailbreaking.
http://news.cnet.com/8301-13578_3-20011661-38.html
I doubt it myself but it doesn't negate the fantasy value of the idea.
