This is very interesting. There are a lot of brand-sensitive client types such as healthcare organizatons and higher education who would love this. I do have one question though.

According to Wikipedia's list of software and search engines that support OpenSearch, only Google Chrome is on the list. [1]

Google as a search engine is not listed. The screenshot in the article is also in Chrome.

I wonder if this feature is supported in Firefox or IE.

[1] http://en.wikipedia.org/wiki/OpenSearch

edit: tested in Firefox, it works. this is great!