Mozilla developers have now uploaded Firefox 22 to the web.
No official release announcement has yet to come over the wire, but Firefox 22.0 is now available from the Mozilla FTP server
Firefox 22 changes include enabling Web Real-Time Communication
Some other prominent changes include use of the new web notifications API, ASM.js optimizations, the pointer lock API is now supported outside of the full-screen mode, and much more.
Stay tuned for more details in the official Mozilla Firefox 22 release announcement.