It sure does. That's the story indicator line. It corresponds to which story you're reading. In Google Reader, that line is invisible and is roughly half way down the screen. As you move your mouse, the story that is underneath that line is the currently selected story.

If you lock that indicator, it waits until you scroll to select the story. Google Reader's position is locked, so if you want to emulate Reader, just lock the indicator just about half-way down the screen. Personally, I prefer having it follow my mouse.