It's done and added to next patch.
Just like the ingame hourly messages, it displays the time since you opened FGunZ, so the time of the current FGunZ session. The time displayed on fgunz.net is more accurate, which is only updated once you log off.
I guess :online: should be good as shortcut.
I have also added :time: and :fps: so you can inform others about your current local time and your current FPS.