amazon released "Simple Queue Service" and "Browse Node API".
Browse Node API is actually a new operation in Amazon E-Commerce Service. According to Amazon, it provides information pertaining to a Browse Node. Browse Nodes are product categories that Amazon creates to segment products based on pre-defined and/or dynamic criteria.
I think that much more interesting is Simple Queue Service, which is (as far as I know) the first "generic" service offered by a big web site. The Simple Queue Service offers a reliable, highly scalable hosted queue for buffering messages between distributed application components! Which means you can use it for any web application, even if it is not related to Amazon!
