Skype doesn't work in Karmic Koala
I had to uninstall the Jaunty package from Multiverse…
apt-get remove skype skype-common…and then re-install the 8.10+ version from Skype. You may need to restart pulseaudio and mute and un-mute the microphone it working again.
dpkg -i http://www.skype.com/go/getskype-linux-beta-ubuntu-64http://friendlytechninja.vndv.com/2009/10/16/howto-install-skype-on-ubuntu-9-10-karmic-koala/