Since lot of us have to wait for the newer versions to appear in repositories I wanted to include this quick script for Debian based distros which i found somewhere on the net ... (sorry don't remember the site but IT'S NOT MY WORK)

the only changes are RC2 has been replaced by RC3 since it's the latest
................................................................................................
#!/bin/bash
echo "Updating repositories list
"
sudo apt-get update
echo "
Making sure libstdc++5 and the old Firefox are installed
"
sudo apt-get -y install firefox libstdc++5
echo "
Backing up old Firefox preferences
"
cp -R ~/.mozilla ~/.mozilla_backup
echo "
Changing to home directory
"
cd
echo "
Downloading Firefox from the Mozilla site
"
wget -c ftp://ftp.mozilla.org/pub/mozilla.or...-2.0rc3.tar.gz
echo "
Unzipping the .tar.gz file
"
sudo tar -C /opt -x -z -v -f firefox-2.0rc3.tar.gz
echo "
Removing the unzipped .tar.gz
"
rm firefox-2.0rc3.tar.gz
echo "
Linking plugins
"
cd /opt/firefox/plugins/
sudo ln -s /usr/lib/mozilla-firefox/plugins/* .
echo "
Linking launcher to new Firefox
"
sudo dpkg-divert --divert /usr/bin/firefox.ubuntu --rename /usr/bin/firefox
sudo ln -s /opt/firefox/firefox /usr/bin/firefox
sudo dpkg-divert --divert /usr/bin/mozilla-firefox.ubuntu --rename /usr/bin/mozilla-firefox
sudo ln -s /opt/firefox/firefox /usr/bin/mozilla-firefox
echo "
The new Firefox is installed."
.....................................................................................................

1. save it as something.sh
2. chmod +x something.sh
3. ./something.sh