I just upgraded my machine at work to OS X 10.6 (Snow Leopard). It is one of 4 machines that I regularly work on. I keep the passwords and PIM data on these machines synced using MobileMe. Upon the first run of the MobileMe sync process after the upgrade, I got this dialog:
So apparently I just need to guess.
Since the release of MobileMe, the “automatic” setting for sync preferences has been a bit of a farce — at most, it would sync your data up to the cloud once every 15 minutes. With the release of OS X 10.5.6, finally you can rely on your desktop updates being propagated within a minute very handy for those of us who like to make a calendar entry, put our macs to sleep, and walk out of the house without stopping to worry about manually running a sync to make sure our iPhones get our updates.
From their release notes:
Contacts, calendars, and bookmarks on a Mac automatically sync within a minute of the change being made on the computer, another device, or the web at me.com.