Apple is shutting down the MobileMe web service today, but they are still allowing users to migrate to iCloud for a limited amount of time. I would suggest backing up your data now. Apple notified users about MobileMe’s closing a while ago so this should not come as a surprise. They planned to discontinue the service about a year ago. iCloud’s 5GB of storage is free. iCloud can sync across all of your devices including the Mac, iPhone, iPad, and some Windows machines.