Drupal for Firebug extends the Firebug module to provide Drupal specific debugging and status messages. It allows users to see the processing of the node, form, and user objects and works with the Devel module to display SQL queries and execute PHP from the Firebug window. It incorporates jQuery 1.26 for added UI improvements.
You must download the DrupalForFirebug Drupal module to use this extension: http://drupal.org/project/drupalforfirebug
To have the most up-to-date version of the addon possible, please download the alpha* from the Developer Channel at the bottom of this page. Or you can goto the project page over at bitbucket https://bitbucket.org/frob/drupalforfirebug/downloads and download the latest release.
* The alpha version is just the same version that was submitted to mozilla. Mozilla must manually review every plugin before they will allow the release.