Check out that screenshot about the current state of splitting a Nautilus window:
The exciting thing is that this is not a screenshot of my split-view branch, but of Gnome git master.
So after successfully using the split view branch for Nautilus for several months, and (mostly thanks to the PPA) getting some feedback from others, I finally requested a review for it. Turned out that I had a good timing, because with the upcomming Gnome Shell, a debate is currently going on anyways about the future role of Nautilus. With a possible switch away from being a desktop shell and towards more typical file management tasks, split-view fits better into the picture as it used to.
I am very happy that Alex Larsson picked up the task to review and clean up the branch. Even more so as he recently commited a reviewed version to Gnome git master, which can be seen in above screenshot.
The UI is not yet final, and there are a few issues still to be worked out, but I really like the route that it's going. So, if all goes well, there won't be any Nautilus packages for Lucid in my PPA..