OSX 10.7 File Sharing does not respect Group: Everyone "No Access". Share publicly displays
Any folder added to your shared folder list is broadcast publicly. If you don't want it to be visible to guest users, remove it from your shared folder list. You will still be able to access it by logging in as a registered user, using your user name and password. If you log in as a registered user, you will be able to see all your files, but a guest can only see files in the shared folder list.