However, you can publish calendars from iCal, then subscribe to other calendars in iCal. This subscribed information is sent to MobileMe.
I would recommend setting up two accounts on the MacBook Pro so you each have your own workspace, and you can both put in your mobileme accounts separately in each separate account.
Subscribed calendars are not currently syncing to MobileMe. I added Apple's holiday calendar and sync'd up and it wasn't there. I had to export the calendar, delete the subscribed calendar and import the calendar as a local one. Then, poof they all showed up on MM and my iPhone.