Hybrid clouds are the Big Foot of cloud computing: tantalizing but difficult to conceive of and frustratingly elusive to the point of arousing deep skepticism on the part of potentially interested parties. Are they real or a myth?

The public cloud is more and more a fact of life. Indeed, public cloud computing snuck in the back door of both the consumer public and the enterprise: millions of consumers were using public e-mail services before they'd heard of the term cloud computing, and software-as-a-service was embraced by business unit managers before CIOs became comfortable with the idea.

Private clouds are now the hot-button point of debate in the cloud computing community. Some question whether there is anything truly new about private clouds, while the exact definition of how they work seems to be a moving target. (Here's a good explanation of private cloud computing, with plenty of informative links).

Revolutionary or not, private clouds make sense to potential users. Research firm IDC, at its Tech Outlook event in Seattle this week, discussed its data on the trend: "In a recent survey, IDC asked IT executives about their preference for using a private versus a public cloud. Fifty-five percent said that a private cloud was more appealing than a public cloud, and 22 percent said they were equally appealing, said Frank Gens, an IDC chief analyst."

Hybrid clouds, however, are something of the holy grail of cloud computing. At the Structure 2010 conference, a group of industry experts talked about the potential for hybrid clouds as well as their current incarnations, which mostly seem to involve concurrent cloud computing strategies, a combination of private and public, rather than truly integrated ones.

The real potential of hybrid clouds will be realized when organizations are able to swap processing between internal and external resources and spread applications across those boundaries. But how far off is that? One conference panelist expressed the hope that, "[T]he industry will begin to develop common APIs that work across both public and private clouds and allow applications developers to make use of both seamlessly…"

Which is the definition of a truly hybrid cloud approach. How soon? Stay tuned.Hybrid clouds are the Big Foot of cloud computing: tantalizing but difficult to conceive of and frustratingly elusive to the point of arousing deep skepticism on the part of potentially interested parties.