Quote:
Once you convert, Mail, Contacts, and Calendar move to iCloud and are no longer available via MobileMe.

Mail is still accessible via the Mail app in OS X. Calendar via iCal appears to be inoperable on my laptop that has yet to be converted. Can't say regarding contacts. So using the OS, mail still works on Macs that haven't been converted =)

Haven't tried stuff via the actual MobileMe web interface ...