"Wolf" Rentzsch has discovered an undocumented anti-caps lock function whereby the keyboard will not register a very quick press of the caps lock as sometimes happens by accident when reaching for the left shift key. You can still activate it by pressing and holding the key. Rentzsch notes that if caps lock is already active a quick press will disable it, confirming that this is an intentional feature. He posts a little video to demonstrate.
This is vintage Apple: thinking about and implementing the little things that make your computing life just a little better.