Boot to Gecko
This is Mozilla’s way of making the web be a capable platform for the mobile world. Instead of having to write Objective-C, or Java, and then, only being able to distribute through certain walled gardens, Boot to Gecko makes websites first-class citizens.
This means developers only need to make a website, using technology they already know, and their app is freely available (or they can charge, of course) to anyone who’s mobile device implements the modern web.
This is big.