Google finalmente liberou a versão do Google Talk com som e vídeo para os usuários do Linux.

Caso use Ubuntu: http://www.google.com/chat/video

Clique em "Install", faça o download do .deb e instale.

Update: Para sistemas Debian:

32 bit:

mkdir goog; cd goog
$ wget http://dl.google.com/linux/direct/google-talkplugin_current_i386.deb
tar vx google-talkplugin_current_i386.deb
$ sudo tar xvzf data.tar.gz -C /

64 bit:

mkdir goog; cd goog
$ wget http://dl.google.com/linux/direct/google-talkplugin_current_amd64.deb
tar vx google-talkplugin_current_amd64.deb
$sudo tar xvzf data.tar.gz -C /

Reinicie o Firefox.

Fonte: http://www.webupd8.org/2010/08/google-voice-and-video-chat-comes-to.html