If there’s any phenomenon that will move enterprises out to the Web in a big, impactful way, it’s Software as a Service, or SaaS. If it catches hold, SaaS will begin to change the mindset of many business leaders — that the Web has many resources to offer that can be done in a faster and better way than having companies continue to struggle with their own IT and applications management.

But we’ve heard all these promises before, haven’t we? Most recently, the ASP (application service provider) and managed hosting trends that arose in the mid to late 1990s promised to free enterprises from the drudgery of IT management. But the economic foundations of the ASP industry were too shaky. Security was an overriding concern. Availability was not a sure thing. And, more than anything else, control was an issue — executives did not want to hand over control of critical IT assets to outsiders.

However, recent studies and quotes from industry leaders suggest that perhaps SaaS is a phenomenon that is now gaining steam. A new report out of Saugatuck Research, for example, declares that “SaaS is now beyond the ‘tipping point .’” The firm’s latest survey of 250 IT executives shows that not only have more than 26 percent of companies installed at least one SaaS application, representing nearly 150 percent year-over-year growth, but resistance has plunged dramatically, in terms of firms that are not planning to deploy SaaS.”

Saugatuck adds that another 20 percent either prototyping, implementing or planning to install their first SaaS application in 2007.

I just published an article on the SaaS phenomenon in the April issue of Database Trends & Applications, for which I spoke with SaaS movers and shakers at both Oracle and IBM. Robert Reid, group vice president for Oracle’s CRM On Demand service, said that “a majority of Oracle enterprise customers” are now deploying Oracle’s CRM applications through its SaaS-based delivery service.

Dave Mitchell, director of software-as-a-service strategy for IBM who is in charge of Big Blue’s partnerships with SaaS ISVs, said that “most of the start-up application vendors are selecting SaaS as their primary model, and increasingly as their sole model for delivering applications. It’s gotten to the point now where most of the venture capital firms are only investing in ISVs that deliver their applications as a software service.”

Saugatuck predicts that the next surge of growth will come from large enterprises that are now beginning to view SaaS as “just another part of the fabric of enterprise IT.” Saugatuck calculates that on average, the typical large enterprise now taps into at least three SaaS applications, with one in seven having greater than 10 SaaS applications.”

Users are growing increasingly sophisticated about SaaS as well, and are “newly fluent in such concepts as multi-tenancy, web services APIs, data and workflow integration and mashups — even though users may not require them all in the SaaS business services they contract.”

However, some industry experts have words of caution about SaaS. Steven Mocarski, CTO of Singularity Design, for instance, told me that he would not recommend SaaS to his larger clients, based on concern with security, particularly of intellectual property or other key strategic information:

“I would not recommend it for any of our large clients,” Steve said. “While we’re happily using SaaS in a number of areas, due to our high growth and increasingly more sophisticated and demanding IT security requirements, we’re planning to move away from SaaS applications for any core functions by 2010. We may reconsider if SaaS vendors provide uptime, responsiveness and integrity assurance in real terms (read: from our location, not theirs) in addition to the obvious need for security and privacy. Those kind of guarantees would require SaaS vendors to go way beyond simply offering a service on the Internet — it means working with connectivity providers/experts and I don’t know if they’re ready to do that.”