Can we all stop talking about "the cloud" please? It makes responding to this kind of article far more difficult. After all, you can't really compare something like Dropbox with EC2 - they do completely different things and there is really very little in common. If you're talking about remote file storage, call it that. Don't get Hung up on this mythical "cloud".
It is a little irritating to think of people using cloud services without local backups. It is trivial to backup Google Documents but some data is more of a challenge (e.g., local copies of AppEngine datastore, SimpleDB, etc.).