Firefox comes with a new Download Manager in the Firefox toolbar, so you can monitor, view and locate downloaded files without having to switch to another window.
For developers, Firefox includes getUserMedia, an important part of the WebRTC specification. It allows developers to quickly and easily write code that accesses the userís camera or microphones. Firefox also includes a developer toolbox that provides quick access to developer tools in one convenient window and gives developers easy-to-remember ways to switch between tools. Canvas Blend Modes allows developers to define how they want Canvas to draw over an existing image to create different visual effects.
Firefox includes a new enhancement to private browsing that allows you to open a new private browsing window without closing or changing your current browsing session.
Careful with this, it's not necessarily more secure depending on how they implemented it. Think global passwords here, if each individual page is getting centrally stored data of ANY kind then this would actually be much less secure.