Microsoft has had such a service for a few years now, they call it SkyDrive. Unfortunately it wasn't a very good user experience when I last looked at it. It's been a while though (and I just use Dropbox now), so it might have gotten better.

Microsoft may have just been too early. Once they recognize the success they can clone the usability in no time. Or patent troll Dropbox off the map. Very risky investment if you ask me.

That said, Dropbox is a great product and the free version is good enough for the small number of documents that I have that are not somewhere else in the cloud.

But the question is wether that justify the high evaluation . I thing ms and apple are going to get their act together before that prize is ver realized. But that's just me.

It does not justify the high valuation. That's what I meant with "clone the usability in no time".