Correct me if I'm wrong, but in order to install apps from Amazon (or any provider that isn't the Android Market) you will have to allow third party apps, correct? Isn't this a security hole? I mean, it's not that I don't trust Amazon, but once your phone is set to allow third party apps, you can install ALL third party apps, from anyone. Now, I'm not stupid enough to download any old random app to my phone, but not everyone has such common sense. I can see the number of infected Android phones skyrocketing if Amazon or another competitor succeeds and actually takes a foothold in the Android app market.
I don't agree with Apple's walled-garden approach, being able to install third-party apps is nice, but for 50%+ of the population, it's an unnecessary security risk. A lot of people are really, really stupid when it comes to technology.
Ugh, I like competition and all but wasn't the point of these app stores in the first place to provide an easy, centralized way to get applications (kind of like the software repository system in GNU/Linux OSes)? If Amazon has an app store with exclusives, then it is entirely possible that another retailer will open up their app store and get exclusives. Before you know it we'll have 15 competing Android stores and people will be confused which app store has the program they want or where they got such and such program from. Then imagine having 15 different app store applications to have to search through to find applications.
Maybe it won't be as bad as I'm imagining it to be, who knows.
For enabling third party software installs I suppose you could have a whitelist of software sources. You could have Android Market only, Android Market, Amazon and any other major store, and all sources. In the end though, that is still going to confuse a lot fo people.
The Amazon appstore was said to have only 3800 apps in store. This seems to be a small number, considering that you can find, using any files search engine like FindFile.net, http/www.findfiles.net , a few thousand free Android apps for downloading in the net.