It seems like a wise strategy, given that even the IBM customers brought to a company event here to showcase their cloud development efforts were either not using the public cloud at all, or still in the early stages with it.

Tony Kerrison, CTO at financial services firm ING, said his company is running "zero" applications today in the public cloud. Like other financial services firms, ING is heavily bound by regulatory requirements, as well as strict European Union rules about where its customer data can be stored.

Even putting e-mail in the cloud, which is first on Kerrison's wish list, will be "a challenge" because of the regulatory issues, he said in an interview at IBM's in San Francisco, where IBM announced its latest public and private cloud offerings.

Carlos Matos, senior director for infrastructure management and systems integration at Kaiser Permanente, said his company "dipped our toes" into a cloud initiative this year. Scott Skellenger, senior director for global IT operations Illumina, a life sciences firm that provides genotyping services, declined to specify what applications, if any, his company is running in the cloud.

That's not to say IBM doesn't have plenty of customers using its cloud services. But it highlights the challenges of getting enterprise customers, especially in data-sensitive industries such as health and finance, to embrace public services.