Update Indicator GNOME Shell extension displays new updates on the GNOME Shell top bar. Using it, you can see a list of available updates, update the software sources or install the updates with a single click.
Currently, the number of available updates is displayed in the center of the GNOME Shell top bar, next to the calendar and unfortunately there are no settings to move it for now.
The extension was updated yesterday to support the latest GNOME Shell 3.2.1 (without having to tweak the version in the metadata file) and is available in its developer PPA - install it in Ubuntu 11.10 Oneiric Ocelot using the commands below:
sudo add-apt-repository ppa:aegirxx-googlemail/gnome-shell-extensions sudo apt-get update sudo apt-get install gnome-shell-extension-updateindicator
Once installed, reload GNOME Shell and use GNOME Tweak Tool to activate the extension.
If you're not using Ubuntu, download UpdateIndicator GNOME Shell extension via Launchpad (use: "bzr branch lp:updateindicator" to get the code).
For a similar tool but for Unity (uses Ubuntu appindicator), see: Update Manager Indicator For Ubuntu Brings Old Update Manager Behavior With Extra Features