As recently as a few years ago, ventures into the cloud were mostly experimental, back-burner projects, not something to which companies would trust critical data, says Chris Silva, senior vice president of research and service delivery at IANS Research, an information security research firm. Today, "we're seeing a lot more things taking on a cloud flavor," Silva says.

A growing number of businesses are seeing value in services that provide increased processing power for busy times, such as holiday shopping seasons or financial reporting periods, Silva says. "This has moved from fringe activities to the mainstream."

Into the Cloud: The Business Case Rules

To be sure, some companies are still reluctant to use the cloud for customer and other sensitive data because they have security and regulatory compliance concerns. Nevertheless, businesses are forging ahead with cloud initiatives, and, as with other significant IT investments, decisions about whether to use the cloud and which services to adopt often come down to whether there's a strong business case.

"The economics and business needs are going to determine what stays on-premise versus lives in the cloud," says Doug Menefee, CIO at Schumacher Group, which provides emergency-room-management services to U.S. hospitals.