Those surveys are grossly inaccurate, according to many of the same analysts who conducted them, because they don't count the business units that are buying cloud services behind IT's back.

In 2010 only 13 percent of IT decision makers said their companies were already using external infrastructure-as-a-service (IAAS) clouds and planned to expand that use.

"The actual number was double that, and that was only talking about IAAS," according to Galen Schreck, vice president and principal analyst at Forrester Research.

Even Schreck's anecdotal number underestimated the gap between how many cloud apps IT thinks an organization is using and the real number, according to Frank Gillett, VP and principal analyst at Forrester.

"Informal buyers" from outside IT buy IAAS twice as often as "formal" buyers inside IT, and the informals make five times as many software buying decisions as the IT people who are supposed to be in charge, according to Forrester.