Jonathan Zittrain explores some of the downsides of the incipient cloud computing revolution in this article at the New York Times:
If you entrust your data to others, they can let you down or outright betray you. For example, if your favorite music is rented or authorized from an online subscription service rather than freely in your custody as a compact disc or an MP3 file on your hard drive, you can lose your music if you fall behind on your payments — or if the vendor goes bankrupt or loses interest in the service.
The crucial legacy of the personal computer is that anyone can write code for it and give or sell that code to you — and the vendors of the PC and its operating system have no more to say about it than your phone company does about which answering machine you decide to buy.
This freedom is at risk in the cloud, where the vendor of a platform has much more control over whether and how to let others write new software. Facebook allows outsiders to add functionality to the site but reserves the right to change that policy at any time, to charge a fee for applications, or to de-emphasize or eliminate apps that court controversy or that they simply don’t like.
As useful as storing links, calandars, emails, and documents in the cloud is I like to keep local backups of all my stuff (where possible). The further threat to the decentralised innovation that has characterised software development over the last several decades is another reason to be sceptical of the benefits of the cloud.