All these systems are doing it wrong. I don't want online backups, I want an infinite, encrypted, online filesystem. I should be able to mount it and treat it like any other hard disk. The local disk should just be used as a huge cache. I can't find a service that does this. Why the hell not?

But it's unclear if this is what "everyone else" wants as well. The most interesting group, I think, is not the mostly tech-illiterate who want to store their garden pictures and videos in the cloud, nor the tech-elite who are willing to trust online storage with large swaths of their lives and businesses.

It's the group in between that is the most interesting to these companies right now. Those who are relatively well informed about major technologies and their uses. Do they really want to have their information mostly stored off-site, or do they simply want larger and larger local storage mirrored by online back-up for peace of mind and easy sharing?

I would guess that this is the largest (apparent)consumer market and one of the reasons why this is where most of these companies have their focus right now.

This seems close to what you want, but not quite there.

http://code.google.com/p/s3fs/wiki/FuseOverAmazon

I'm almost ashamed to admit I'd never heard of either of these before. Will definitely check them out.