I've re-installed jaunty final today after trying out kubuntu 9.04 and when I went to system - administration - hardware drivers but nothing was offered (incidentally the exact same thing happened when I tried out Kubuntu) I also had problems in finding the ubuntu restricted extras which weren't offered under the add remove programs, some of the regular programs I use were offered but some weren't, eg. vlc media player wasnt offered either. I then went to system admin then chose software sources and changed from the UK to main server then the system hung. I restarted the pc and then replicated the above but this time I was offered the graphics card drivers and I was also able to download the ubuntu restricted extras however vlc still wasnt offered. I restarted the pc as you have to when you download the graphics card drivers and then went back to add remove programs to try and get vlc which this time it was offered. Using the same hardware and same procedures I've not had any problems like this when I used Jaunty beta, alpha and rc builds.
Did you update your system in the day of release of jaunty? Possibly due to heavy traffic there might have been some timeouts...