Having already went through the Aurora stage, Mozilla's next Firefox release, version 5.0, has went into public beta and is now available for download from virtually anyone running a Windows, Mac OS or Linux system.
The Firefox 5.0 beta comes with multiple fixes as well as goodies like:

- support for CSS animations
- support for switching Firefox development channels
- moved Do-Not-Track header preference (for easier discovery)
- improved canvas, JavaScript, memory, and networking performance
- improved standards support for HTML5, XHR, MathML, SMIL, and canvas
- improved spell checking for some locales
- improved desktop environment integration for Linux users
Testers can get a hold of the beta build via this page .