New today: the Surface icon in the left panel. When you've gone deep — into a story, a profile, or the flipped view — one click brings you back up to the timeline, with the cursor on the post you were just reading, scrolled into view.
It's not the same as Home. Home takes you to the top and starts fresh. Surface is a lifeline: however deep you get buried in a thread, it puts you right back where you left off.