In general, cloud computing is not good for privacy. For documents stored on the cloud, not only is there the same risk of hacking that is present for all electronic documents, but there's also a risk that the cloud service provider will accidentally share your data with other clients or users who don't have your permission to see it (see, e.g., Google Privacy Blunder Shares Your Docs Without Permission). However, now, a group of technology companies is coming together to try and address some of the concerns related to cloud computing with a positive change in the law. As described in this article, the group, calling itself the Digital Due Process Initiative, is pressing for the law regarding access to electronically stored information to be clarified, and the protections for that information to be strengthened.
To my mind, this is a positive development. The law on what protections are afforded to electronic communications is not at all clear, as there is currently a split between the First Circuit's decision in U.S. v. Councilman and the Ninth Circuit's decision in Konop v. Hawaiian Airlines on the question of when (and if) the protections of the wiretap act apply to email (see here). While clarifying that (and preferably strengthening existing law) won't eliminate problems that could be caused by cloud service providers accidentally sharing data, if the coalition succeeds, it would change cloud computing from a phenomenon which is almost wholly destructive of privacy, to one which could have beneficial effects, at least in terms of lobbying and raising people's awareness of the issues.