We support Desktop Notification now: if you want to test them, use that page and a recent Nightly: http://jsbin.com/notification/522/edit
Especially interesting is the way sites must require authorization before to be allowed to use these notifications:
We have now a new Baseline Compiler for SpiderMonkey: it allows us to show significant performance improvement: https://blog.mozilla.org/javascript/2013/04/05/the-baseline-compiler-has-landed/
A network monitor landed in the dev tools of @FirefoxNightly last night. Great work by Victor Porof!
ES6 `Object.is` is now support by @FirefoxNightly - See http://mzl.la/YkgPGq
Fx Nightly is about to support HiDPI favicon (on HiDPI systems): https://bugzilla.mozilla.org/show_bug.cgi?id=828508
ES6 Arrow function syntax has landed in @FirefoxNightly: `let square = x => { return x*x; };` Spec: http://is.gd/VsW9oT
Multithreaded image decoding coming to @FirefoxNightly: http://bugzil.la/716140
in @FirefoxNightly: Download progress in app icon in Mac OS X Dock : http://imgur.com/KAHfkt2
asm.js in @FirefoxNightly: https://blog.mozilla.org/luke/2013/03/21/asm-js-in-firefox-nightly/
Parallel JS lands in @FirefoxNightly : http://smallcultfollowing.com/babysteps/blog/2013/03/20/parallel-js-lands/
