Hi,
I've not seen this in Vista, but -sorry to say this- in itself and from reading the description it seems like a tacky and superfluous thing to me.
I wouldn't say it's superfluous nor tacky. Did you try it?
+1If it's going in the clock app (rather than prefs) it can't do any harm - it can just be an option to toggle
That's what i think. Time prefs might not be the right place, but I know a lot of people that like all those desklets and for sure there are people that would enjoying this feature too.
Best regards, Karsten