Adding placeholder text to all search fields.

This is done using the HTML5 'placeholder' attribute, plus a jQuery
plugin to emulate its behavior on older and non-supporting browsers:

http://code.google.com/p/complete-placeholder/source/browse/jquery.complete-placeholder.js

http://www.thoughtswordsdeeds.com/2011/07/a-complete-placeholder-fallback-solution-for-html-5/