Amazon has been introducing new products to its Web Services Porfolio. Its API is one of the most praised out of all the APIs that have been seen over the past few years. The webservices system is built for publishers to make money, and I if I recall the figures were about 975,000 active Sellers and 120,000 active developers integrating the amazon services.
24% of Amazon Sales are made from its publishers. However in answer to your question the third party developers are more likely to launch such a program via a mashup application than Amazon doing it themselves.
I believe there is a startup company in the UK called inside C who have launched a contextual messenger application called "inside messenger" where as if you were to type in the name of an author or book while in a chat session it would automatically display the book.
The Web Services Publisher Program has been about since 2002, it is a fantastic program and they do claim that 90% of all publishers have sold at least one item in the past year.
http://www.ipoj.com/w8jwS (short link to the program)