I definitely recall it working in the old forum, although it was quirky - if you visited a forum and then came back later it would have marked all topics read, not just the individual ones you visited. I remember clicking individual threads open in a new tab so the main sub forum page would remain the same read-status wise.
Here it seems IPB has some rather large overhead for topic read tracking. Too much for a community of our size to handle, so we've disabled it to improve performance. I've simply gotten in the habit of clicking the Mark All Read link when I'm done with a forum