Well, actually, to the same account, right? You can have two phones sync to the same account with different sets of calendars syncing to each phone.
In our case, I have my calendar, my work calendar, my projects calendar, etc, etc, my wife has her set, but then we would like to have one joint Home calendar for things like social events that we both can edit.
We *could* merge everything into one big mess on a single account, but instead we use MobileMe... but we can't jointly edit that one calendar. One of us owns it, the other can subscribe, but read-only. This is less than optimal.
With a copy of Server, you can set up a calendar as truly shared among many users.
What's funny is that I bought a mini just a few months ago, and moved all of our services (mail, web, etc) *OUT* of the house (was running Server!), because I got tired of doing my own hosting, and wondering if the net would go down or power would go out when we were on travel.
