I meant to post this the other week but forgot, but a clean install has just prompted me to add it again. Found via Digital Minute
Digital Media also have an updated post about styling the console.
- Click on the Bookmarks menu and select Manage Bookmarks&
- Click the New Bookmark toolbar button
- Enter chrome://global/content/console.xul as the location
- Check the Load this bookmark in the sidebar checkbox
- Click OK