I've been trying to add stuff to the panel and to change the order of the icons in the launcher but there's no effect. It's like the changes aren't saved. I change something, close dconf editor, lock out and back in again and nothing changed.
The 3D version of Unity is implemented as a plugin for Compiz, so uses Compiz's preferences store (separate from the preferences stored for the 2D version of Unity).
Those preferences are still stored in GConf (which can be edited using the
gconf-editor program). The settings you are probably interested in are found under
Alternatively, you can use the
compizconfig-settings-manager to get a slightly more structured view of the plugin settings.