[Swing]

This does not do exactly what you ask, but I had the same desire and so in Preferences went into Acounts and specified iCal as a log-in item (so that it starts automatically).

So at least the date in the iCal dock icon is always correct, and you save menu bar space. Of course, you are using system resources via this method and so if you do not use iCal it is probably a bad idea in any event.

EDIT: I use the analog clock in the menu bar and so I think some of the customization parameters which may otherwise solve that menu bar issue are not available. And so I went the iCal dock route.