Comment 11 for bug 595555

In case anyone is still looking for an answer, I've found a solution:
Since the screensaver is now handled by gnome, I checked the Configuration Editor. You'll find the screensaver settings in there under apps -> gnome-screensaver. I noticed that the "idle-delay" key was NOT set to the value I put in the gui settings (System->Preferences->Screensaver) which was 1 minute. It had 10 instead. Once I set it to 1 minute the screensaver actually started at 1 minute instead of just fading and coming back to the desktop. Hope this helps.