The expanded mode you're refering to got nuked in it's current format. This is something I do want to bring back, but somewhat different. Unfortunately this probably won't happen until version 7.1. The problem with the old expanded mode is it added alot of extra overhead and bandwidth that was unnecessary at times.
What I mean is this. Say you're showing 20 topics per page. Your interested in only 5 of those topics. It would expand all of the topics anyway, leading to a huge page. What I'd like to do is, utilizing AJAX of course, is to offer a way to only expand certain topics. Basically, something like a little + next to the topic, you hit it and it retrieves the expanded post list of that topic.
