I can confirm this bug and the workaround.
If I use the default login on a vanilla Xubuntu 8.04 install, the screensaver does not activate and locking does not work.
If I select Xfce login in GDM, it all works correctly.
I can confirm this bug and the workaround.
If I use the default login on a vanilla Xubuntu 8.04 install, the screensaver does not activate and locking does not work.
If I select Xfce login in GDM, it all works correctly.