This is a good point. Those companies have created great brands and understanding what they've done with web services and developer logos/branding, etc., would be really useful.
I'm working on understanding their terms and what the foregoing prohibitions are, but this doesn't look very encouraging:
The foregoing prohibition includes the use of "amazon," any other trademark of Amazon or its affiliates, or variations or misspellings of any of them, in the name of an Application or in a URL to the left of the top-level domain name (e.g., ".com", ".net", ".uk", etc.) -- for example, a URL such as "amazon.mydomain.com", "amaozn.com" or "amazonauctions.net" would not be acceptable.
More when we know more.