iOS Devices Do Support Amazon Cloud Player--Somewhat
Amazon's Cloud Player online music locker service enables users to upload their own music to Amazon Cloud, and then stream them to any standard web browser--even Google Android devices. Recently Amazon made some tweaks, and the iOS web browser is also supported.
By using HTML, rather than Flash, the Amazon Cloud Player works through the Safari browser on the iPhone, iPod Touch and iPad. When you are listening to music being streamed via Amazon Cloud Player and you receive a phone call, the music pauses.
Although the experience is less than luster on a small screen, the iPad is likely a much better platform for Amazon Cloud Player, and Apple isn't likely to want to work with Amazon to make things any better. They are said to be working on their own streaming service via iTunes, but in the meantime, Amazon Cloud Player is here.