With PPT 2010 the animation has a new trick. When editing a slide the Animation Pane can be opened in its standard right-side position.
But when switching to Slide Sorter view it automatically closes.
It is a minor thing, but the animation pane is of no use in slide sorter view. In all early versions it remained open/visible just taking up screen realestate. And when you go back to editing a slide it appears open again until you close it.
– Troy @ TLC