Firefox 20 beta is out now. Brought 2 pretty big changes. One is that you can have a private browsing window and regular window open at the same time and two is the brand new download manager that is up by the search bar.
IIRC, The new download bar appeared in a build that was slated for 17 but then disappeared. I'm glad to see it's back in 20. No more of that separate download box popping up ever again!