This bug is still in sp11.
I'm looking at
http://www.encyclopedia.com/html/c/crayfish.asp and the back button doesn't work unless I turn off ad blocking from blocked URLs.
What seems to be happening is that when the ad is blocked, the page being loaded is loaded into the back list. If the ad isn't blocked, the page loads normally and doesn't go into the back list.
I know that the workaround is to use the back history below the back button. And I know that it's a sort of known problem mentioned in the release notes for sp8. But it's still broken.