Comment 6 for bug 1302793

Although I'm no longer able to install the .deb downloaded from Google, these instruction were successful:
http://www.ubuntuupdates.org/ppa/google_talk_plugin

These 3 commands worked:

wget -q -O - https://dl-ssl.google.com/linux/linux_signing_key.pub | sudo apt-key add -

sudo sh -c 'echo "deb http://dl.google.com/linux/talkplugin/deb/ stable main" >> /etc/apt/sources.list.d/google.list'

sudo apt-get update ; sudo apt-get install google-talkplugin