Today’s preview marks the beginning of Mozilla community testing for the Firefox Metro browser designed from the ground up for Windows 8.
Earlier this year, we began development on a version of Firefox that runs on x86 Windows 8. This version of Firefox runs in both the Windows 8 “classic Desktop” environment, and in the new “Metro” environment. We’ve made a lot of progress since that first development update. We’re excited to share it with you and we’re looking forward to your feedback.
Read more at source:
https://blog.mozilla.org/futurereleases/2012/10/04/firefox-metro-preview/