I have this problem and I'm using OS 10.8.2 on an early 2011 MacBook and the only time I lose the cursor is after playing an iTunes video/podcast on full screen.
The only way I can get the cursor back is to swipe to a different desktop/screen, initiate a hot corner I've set to sleep the screen and then a moment later moving the cursor, bringing the screen alive.
If I go back to fullscreen video/podcast and stop, allowing the player to auto-hide the controls and cursor, I again lose the cursor. This is reproduceable and predictable.
I have not encountered the problem with any other type of video, screen saver, etc. I have all recent updates of all software, including iTunes 11.0.1 (12)
Any fixes yet?