OK, I just upgraded to Firefox 3.6, from 3.5.8. It's still the same, mostly, except one change that I have noticed is that tabs no longer open left to right in the order that you open them, across the top. Instead, tabs open left to right in the order opened, starting immediately to the right of the tab from which you opened them. This is going to take a bit of getting used to.
(In other words: if you have two tabs open, Tab #1 on the left and Tab #2 on the right, when you open a link from Tab #1 in a new tab, Tab #3 will appear to the right of Tab #2. Now, Tab #2 gets shifted over to become Tab #3, making Tab #2 the one you've just opened from Tab #1. I can see the logic for this, but it's one of those differences that's just different enough to frustrate for a little while.)