Sorry, new to Firebug. I really find being able to run javascript in the Firebug console window helpful. However, I don\'t seem to be able to run jQuery calls in the console.
Like others have said, it wont work unless you have jquery included on the page. However, you can easily include jQuery on any page with this bookmarklet: http://www.learningjquery.com/2009/04/better-stronger-safer-jquerify-bookmarklet