It's interesting that when following smartphones Microsoft and Blackberry seem to be afterthoughts - it's pretty much all Android and iPhone. That along with reported sales indicate that Blackberry continues its fall and Microsoft's Windows phone simply hasn't caught on. By the way, we recommend either iPhone or Android for business or personal use because of functionality, not popularity.
Here is the skinny on the new Amazon Android App Store from TechCrunch:
Amazon’s Disruptive Android App Store Now Open To Developers — Full Details