You can check out the script here: ubiquity_search.js. If you have Ubiquity installed, you should see a Subscribe button in the upper right; alternatively you can get the javascript code from the above link, paste it into your Ubiquity command-editor, and edit away.
To use the search command, invoke Ubiquity (Ctrl-Space) and type multi-search (or any prefix) followed by any search terms and Enter. Alternatively, you can highlight a search term with the mouse, invoke Ubiquity and the multi-search command and hit Enter.
Also check out my other Ubiquity scripts. They are all in the public domain; you can use them in any way you like.