The recent release of Firefox 28 brought VP9 decoding and Opus support to WebM among others but it looks like Firefox 29 will be a much bigger change than we've seen in recent years.
New customisation UI in Firefox 29
Firefox 29 (now in Beta) will bring a new menu button and a new customisation UI to allow the user make the browser UI truly personal. Hopefully the Linux version will feature this as well. It's often that these new toys are only for Windows/Mac users and Linux fans get left out.