It's probably due to UDS but it seems Ubuntu 11.10 users haven't gotten their Firefox 8 update yet. Maybe in another week when things are back to normal.
For the impatient
You can get Firefox 8 through the Beta channel PPA. Looks like it's still just Beta 6 though.
~$ sudo add-apt-repository ppa:mozillateam/firefox-next
~$ sudo apt-get update
~$ sudo apt-get install firefox
As usual reverting to the version that comes with Ubuntu 11.10 is just a ppa-purge away.