Gnome Clocks is the first Gnome 3 application for clock, world clock, alarm and stopwatch. It was developed in Google Summer of Code this year and we have covered a lot of articles on its development. The good news is its finally available in Ubuntu 12.10 and users can have a taste of it right away.
You can add several cities of the world in World Clock, set alarms and use stopwatch to measure time. It will not probably be available in Ubuntu Precise as its using Gnome 3.4.
Install it by using apt-get
sudo apt-get install gnome-clocks