IE7 to include “Open Search” using “SCR ” format writes “It’s our goal to make it easy for IE7 users to personalize their list of search providers. The user should be able to target their search directly to site of their choice: MSDN, Intranet portal, Team Sharepoint, PubMed, NYTimes, Costco, USPS, Amazon, WikiPedia, Ebay, Craigslist, etc. My last blog post mentioned we will be adding extensibility for Internet Explorer’s new Search Box in Beta 2. We’re announcing the API at PDC during Chris Wilson’s talk on IE7. Here are the details.

The scenario has two steps:

Users can easily add sites to their list of search providers
Sites describe how IE can interface with them