A9 announced OpenSearch today at the Emerging Technologies Conference. OpenSearch is a list of specifications of how other search engines can make their search results available.
Wait, what was that? Other search engines?
Yes, the idea behind OpenSearch is that other search engines can be listed on A9 if they obey A9's specifications for publishing their data. The "open" in OpenSearch is other people opening their search engines.
A9's OpenSearch initiative would have a lot more credibility if Amazon and A9 started by providing unrestricted access to all of their search engines in the OpenSearch format.
[OpenSearch announcement via John Battelle, Werner Vogels, and Danny Sullivan]