I don't know if any one of you tried this, but to see it
1. Activate the standby screen (make sure the screen tone is "vivid", haven't tried with other tones yet)
2. Go to a completely dark room
3. Cover the clock with a cloth
You'll notice that the black part of the screen flickers at a rate of 1 flick per second. I haven't seen this behavior on the N8 (Anna and Belle screensavers)