I just received this email from the A9 OpenSearch team:
We have just released OpenSearch 1.1 Draft 2. We hope to declare it the final version shortly, and it is already supported by A9.com. Uprading from a previous version should only take a few minutes…
OpenSearch 1.1 allows you to specify search results in HTML, Atom, or any other format (or multiple formats) in addition to just RSS. In addition, OpenSearch 1.1 will be supported by Internet Explorer 7, among other software, so we strongly recommend that you upgrade. Also new is the ability to specify suggested searches, such as spelling suggestions and related queries. (link and emphasis addded)
Woot! I’ll be doing something with this soon.