I recently upgraded to Ubuntu 12.04, and all the gnome shell extensions listed by the Gnome Tweak tool are disabled. What's the easiest way to fix/upgrade them? Do I need to manually delete, re-download and install them?
Go to extensions.gnome.org with Firefox or Epiphany, then to "Installed extensions". Some may me grayed out, that means that they aren't available in Gnome 3.4, but others probably have a green icon on the left with which you can update the extension.
There's also a webupd8 extension for updating all extensions.
Note, the install instructions in the article are wrong, and should actually be:
sudo apt-get install git-core gnome-common git clone git://github.com/eonpatapon/gnome-shell-extension-updater.git cd gnome-shell-extension-updater ./autogen.sh make sudo make install