Public Folders in Mobile Me can be password protected. They can also be set as Read Only, using the iDisk tab of the MobileMe System Preference pane. Here, in a section called Your iDisk Public Folder you will see an option to Allow others to: and you will be able to set this to Read only or Read and Write. If you set it to Read only then while users will be able to see the files you store on your iDisk they will not be able to alter them. If you set it to Read and Write then other users will be able to upload to your Public Folder.…