How do I enable the interactive iPhoto screen saver in OSX Lion?

The Lion features page says:

Interact with photos in screen saver.

New onscreen controls let you pause your iPhoto screen saver and manually flip through the photos in an album without leaving the screen saver.

After upgrading, I've set my screen saver to iPhoto, and it randomly goes through pictures, but whenever I move the mouse, it exits, just like it used to. How do I get this new interactive version?

I have OSX Lion and iPhoto '09.

The screen saver can be controlled with select keyboard buttons. The mouse will wake it up and exit screen saver.

Press space to pause and play. Use the arrow keys (left and right) to move between photos.