Skype 4 for Fedora is only available as a 32 bit version. Nonetheless, you can use install it using yum. Just download it from http://www.skype.com/intl/en/get-skype/on-your-computer/linux/downloading.fedora (or http://www.skype.com/intl/de/get-skype/on-your-computer/linux/downloading.fedora for a german version) and install it with yum.
yum install skype-188.8.131.52-fedora.i586.rpm
After that skype will be working without audio support. This is, because skype relies on the 32 bit version of alsa-plugins-pulseaudio. You can simply install the 32 bit libraries with yum doing
yum install alsa-plugins-pulseaudio.i686
Then start skype and check the audio options. „PulseAudio server (local)“ should be pre-selected. After that, make a test call. Audio should now be working.
If you suffer crackling sound please see http://chakra-project.org/bbs/viewtopic.php?id=6406