iPhone day: Calendar interop picture to brighten soon?

Steve Jobs, quoted by John Markoff: "There’s already corporations who have been running pilots hooking up to Exchange servers and other kinds of mail servers, and they have gone very well." Exchange is also a calendar server. I would love to see a way to wire up one's own calendar server to talk to the iPhone calendar over the air. I will even buy a copy of Leopard if I can do this with the CalDAV server built into Leopard. Then, I would be the master of my own families' calendar sharing, because (hopefully) starting today, that will include at least one iPhone.