It's an replacement icon for the alarmclock or the alarmclock applet in ubuntu. Fits for light panels. Has the same colors as the default ubuntu lucid lynx panel icons.
Replace "/usr/share/alarmclock/alarm-clock.svg" with this one for the application and/or "usr/share/hicolor/24x24/apps/alarm-clock.svg" with this one (only png works here) for the applet.
Run "sudo gtk-update-icon-cache -f /usr/share/icons/hicolor" and restart the application or remove and re-add the applet.
Credits go to rassah. (His profile: http://gnome-look.org/usermanager/search.php?username=rassah)
He made a version for dark panel that can be found here: http://gnome-look.org/content/show.php/Alarm-clock+monochrome+icon?content=124621
I just changed the colors and added a few ticks that it looks good on a light panel.