But perhaps the biggest issue is the lack of standards, says Reuven Cohen, founder and CTO of cloud-computing provider Enomaly. Right now, if a company starts using the cloud services of one provider, it's effectively locked in, dependent on that provider. Cohen believes that companies should be free to move their data to whichever cloud provider they want to work with at any time. In the absence of standards that would make this possible, companies such as the startup Cloudkick have sprung up to help users move data from one platform to another.

Mike Evans, vice president of corporate development at the open-source technology provider Red Hat, compares clouds today to the earliest online communities, such as CompuServe and America Online. "They were all siloed communities," he says. "You couldn't necessarily inter­operate with anybody else until the openness of the Internet came along." Evans believes that open-source projects are "critical" to establishing standards that would encourage more companies to use cloud technology.

Two broadly supported open-source projects may help pave the way for such standards. Eucalyptus, which uses an interface familiar to those experienced with Amazon's Elastic Compute Cloud, provides the means to create a cloud either within a private data center or with resources from a cloud provider. And Hadoop imitates elements of Google's system for handling large amounts of data.

For the moment, Amazon Web Services seems to be the de facto standard, and the company appears not to be interested in defining more formal standards, which would inevitably force it to give up some control over its platform and make it easier for other providers to compete. Says Adam Selipsky, vice president of product management and developer relations for Amazon Web Services: "We think it's very early to understand not only what the standards are, but along what dimensions standards are even useful.