Hover a link. Now without moving the mouse, scroll the mouse wheel. Note that the hovered element is not recalculated: this is easy to check by either having the status bar visible and looking at the target, or making sure you're at a page where links have a distinct hover style (e.g. techmeme.com) and observing the element before and after the scroll. (Found in Safari 3.1 for Windows)
This might be a duplicate of bug 17052
*** This bug has been marked as a duplicate of 17052 ***