I have read in many blogs that old lock screen is replaced by new lock screen in Ubuntu 12.04
But when I installed 12.04 Beta 2 (and updated my system) , its still showing old lock screen. Any idea if its delayed ?
It was suggested and I do remember seeing this on my system somewhere down the road in one of the alphas but later updates removed it.
As you can see from comments
A far as I can tell, it was really awesome but I do remember having some issues that already described on the bug report. Think you will have to wait for 12.10 to see this implemented properly.
Remove gnome-screen saver and install xscreensaver:
sudo apt-get remove gnome-screensaver
sudo apt-get install xscreensaver xscreensaver-gl-extra xscreensaver-data-extra
Set the option to lock the screen after 1 minute.