Apple has posted a guide to help users transition from MobileMe to iCloud. The good news? Just like TiPb's been telling you from the start, there will be web apps for Mail, Calendar, Contacts, and Find my iPhone. Also, if you need more storage, you'll be able to buy it. The bad news? iWeb, MobileMe Gallery, and iDisk are toast.
iWeb, Gallery, and iDisk users are encouraged to move their data off MobileMe before the June 30, 2012 cut off date, and knowledge base articles have been posted to give additional information.