Grateful I am, to be still on the 60 day free trial of MobileMess. It is at least five months from stability, but at least I can see the skeleton of its future. It looks a tad ominous.
Consider the work-home-family calendar triad.
Last week I missed a haircut. I'd entered it correctly on my personal calendar, but the duplicate entry on my work calendar was off by a day. Both calendars live on my Palm (in different applications, which is one of the thousand cuts that killed the Palm), but I missed an alarm.
Typical. Two separate calendars are lousy, but putting my personal appointments on the work calendar is not optimal. Do I want my meetings with representatives of the Zorgonian trade federation to appear on my work calendar? Earth is not ready to learn of those.
Now imagine that synchronizing you work calendar with MobileMe was not a firing offense (at most companies it would be). Further imagine that synchronizing an Outlook Exchange Client calendar with MobileMe wouldn't trash the work calendar (it would ).
You'd still be in trouble. MobileMe is setup so that each user can have a single sync calendar per account. There may be multiple calendars on an account, but you can't sync to them from iCal or Outlook. You'd need to get the family account, and use a different username for each calendar, then share on the family account. I don't have an iPhone or a family account to test this with, but I'm guessing the iPhone would allow sync with only one of the family calendars.
What about Google Calendar, popularly known as gCal? Our Google Apps family calendar allows a very large number of users (100?), so there's lots of wiggle room. There's an open sync API, so vendors can, if they and Google ever get their act together, can implement unidirectonal sync from an Outlook/Exchange work calendar.
From what I've seen of Google Calendar and MobileMe, we're most likely to need gCal. What I fear is that I'll need MobileMe too ... More on that later.
 Maybe the iPhone calendar can sync with an Exchange server, but I'm pretty sure the MobileMe calendar can't handle all the eccentric metadata and relationships that are a part of an Outlook/Exchange appointment - including little details like meeting attendees and recurrence exceptions. This wouldn't be too bad if you could do one way (undirectional) "sync" - send work data to MobileMe. This is not supported however.