After I installed nautilus-elementary on my laptop with a fresh Ubuntu 10.10 (“Maverick Meerkat”), I found myself being stuck with the tree view I had used briefly before installing. There seemed to be no easy way to change back to the Places view, so I dug around a bit:

First off, open gconf-editor by pressing ALT+F2 and entering gconf-editor. Next, navigate to apps → nautilus → preferences. Double click the side_pane_view entry and change the value to NautilusPlacesSidebar. Things should be back to “normal” now, note that this will only take effect for new windows.

Alternatively, you can use the terminal by typing in

gconftool -s --type=string /apps/nautilus/preferences/side_pane_view NautilusPlacesSidebar

Note: if you prefer the tree view, the value is NautilusTreeSidebar.