Fedora 8 was released and some of the biggest improvements were to the audio system. A new daemon dubbed PulseAudio allows much more control over audio streams and the programs producing them. Another big improvement is the inclusion of a little utility called Codeina which allows user to purchase legal codecs for dealing with different media formats. PolicyKit is the new authentication system that aims to make programs that require root access more secure by only allowing certain processes of the program root access.
The full feature list can be found here.