Well, in my excitement I went through the upgrade process for Kubuntu 9.04 aka Jaunty Jakalope but, to my frustration, had some problems.
The resolution was easy however. After restoring all my panels (add a panel to the bottom, add launcher, add task manager, add network manager, add system tray, add digital clock, add show desktop widget) the main problem I suddenly realised was that I was still booting into the 8.10 kernel.
Easy answer from a shell:
sudo apt-get remove linux-image-2.6.27-11-generic
sudo update-grub
Tada, all sorted.