I've made a small python daemon that updates Ambiance when you change your wallpaper. It turns the orange into the same color as the Dash.UPDATE: new working link for the scripthttp://ubuntuone.com/55IAy8Wjz8PDtYbmbFkk4R
$ python ambiance-chameleon.py
Then change your wallpaper.
For some reason, some parts of the desktop are not fully updated: you need to log out or restart unity to see the full effect on the top panel menus and GTK3 apps need to be restarted.