Looks like we got another new feature today. I just noticed that posts are opening as a popup instead of as a new page. That's neat, but I can't see how to go back except by clicking the X (top right). Some other sites use the Escape key to go back.
Edit: Alt-Left also takes you back or click outside the popup. Cannot seem to page down without clicking on the popup first.
BTW I've passed 1000 posts!
The Escape key works for me, I'm using Firefox.
Ah, that works now in Chrome