Read original post at CodeHarder
A handy new feature coming in the Mango update for WP7 devices is the Search Extras. Essentially it allows a developer to deeply integrate his application with the phones experience. [...]
Lets assume that you want to integrate a Craigslist applition in with the search results. From a high level you need to put which extensions you support in you WMAppManifest.xml, add an Extras.xml file with more metadata, and set up URI Mapping in your app. I feel like it is more work than I should have to do, but the tools are still beta, and they could change. Either way it is still pretty easy.