Examples:
Compare the feed of tweets on Twitter.com in Chrome and Safari. When the mouse is kept stationary and the feed is scrolled through using the track pad or mouse wheel, the hover states are not triggered. It seems that the cursor is only targeting elements in Safari when the cursor is moved and not when the browser window is scrolled. This holds true for both CSS and JQuery hover states.
Ex.fm has been able to solve this issue. If you scroll the browser window with a stationary cursor over the list of songs the hover state is triggered. Must be some way to hack this Safari specific issue.