I successfully installed GNOME 3 and GNOME Shell from the Launchpad PPA on my fully updated Natty test system. However, nothing I tried could get it to actually run.
If I selected it in the startup options, I got a plain light blue screen with absolutely nothing on it.
If I tried to start it using
gnome-shell --replace, I got:
gnome-shell --replace &  3251 tim@nattytest:/usr/lib$ Traceback (most recent call last): File "/usr/bin/gnome-shell", line 705, in <module> normal_exit = run_shell() File "/usr/bin/gnome-shell", line 293, in run_shell if shell is None: UnboundLocalError: local variable 'shell' referenced before assignment /usr/bin/compiz (core) - Error: Screen 0 on display ":0.0" already has a window manager; try using the --replace option to replace the current window manager. + Exit 1 gnome-shell --replace
I also tried preceding that with
metacity --replace, as suggested at ubuntuforums.com. But, I got the same failure.
I also linked
/usr/lib/xulrunner-2.0b12/libmozjs.so, which did not help either. No matter what I try, I get the same error messages.