another important thing which i should've mentioned in my last response to keith is that both amazon and apple have created ecosystems which surround their machines. it's not just that they have millions and millions of users, but that this broad base creates an entire infrastructure, because amazon and apple concentrated on that aspect. a lot of the time, this is condemned as "a walled garden", where the criticisms are aimed at the "walled" part of it, but it's also important to understand the "garden" part... the other companies trying to deliver hardware expect us to live in a barren desert, or at best a weed-infested patch. but if/when there is an _infrastructure_ around machinery, it attracts focus and resourcefulness which create synergy. here's an example of that, a browser plug-in which sends the contents of a web-page to your kindle viewer-program:
http://kindleworld.blogspot.com/2011/03/want-to-try-out-free-web-app.html -bowerbird