Just found out another little caveat: To connect to GoogleTalk I had to configure the “Server” setting on the advanced tab in Pidgin for my GoogleTalk Account. Make sure you have “Require SSL/TLS” activated and “Connect server” to “talk.google.com”.

After this, all went smoothly: I was asked if I want to accept a certificate from talk.google.com. After accepting – it worked like a charm.

Thanks for all the work GNU/Linus/Debian/Ubuntu put into this marvelous piece of software – Ubuntu 9.04 is the first distro that I see as fit for the desktop or even a laptop!