I just upgraded to 5 and noticed something odd. I was starting to get into the EventSystem and did not know how to acquire the current EventSystem (other than via Find). So, after googling I found the EventSystem.current static variable that gives back the current EventSystem. So, the thing is, that this is in the documenation (even so in 460) BUT not in the shipped documentation at Unity/Documentation/ which is what I was using (I use Dash on Mac which is on 5 but doesnt show this method either). So to make this clear: Either I'm stupid or you ship at least some parts of old documentation with Unity. You can see that in the screenshots.