In Impress's slide pane on the left:
1. scroll to the bottom (so that the scrollbar "touches" the bottom)
2. make the mouse wheel scroll up one click
Result: the scrollbar jumps to the top instead of scrolling up one notch.
This does not happen if your scrollbar is not "touching" the bottom.
Created attachment 53411 [details]
NOT reproduced with
Ubuntu 10.04.3 x86
Linux 2.6.32-37-generic Russian UI
GNOME 3 specific?
Nope, actually fixed in 3.4.4 it seems!