Comment 45 for bug 428115

> The only unusual thing I had to do when testing is that I had to manually suspend using "sudo /etc/acpi/sleep.sh sleep"

Right, it won't (and can't even) lock the screen with sleep.sh. Please try it with closing/reopening the lid.

> because the suspend option has disappeared in the latest karmic.

This was fixed in yesterday's gnome-session upload.