Multi-tenancy is the most important aspect of cloud computing, according to Salesforce.com platform sales engineer, Clayton Brown.
Speaking at the recent CloudCamp "unconference" held in Perth, Brown said that while some companies continue to pass off ASP products as cloud offerings, "really one of the fundamental things is multi-tenancy".
According to Brown, true clouds - which include Software-as-a-Service (SaaS) offerings - must be public, and scalable to reach a range of customers.
"If you look at Gmail for example," he said. "Google don't maintain an instance for each one of their customers. They invest into millions of servers that can accommodate any number of growing demands of users of that application."
Google's multi-tenancy platform allows them to better forecast peak load and predict growth patterns, while giving them "the scale of economy to keep investing in that infrastructure".
Users also benefit, by getting new features quicker.
"When you have a million users all on this version of Gmail, and the vendor only focussing on that one code line, they're able to innovate and add new features much more rapidly."
Early adopters of cloud computing offerings from the likes of Salesforce.com, Amazon's Web Services and Microsoft's Windows Azure have all shared similar testimonies as to the low downtime rates, the ease of migration and the flexibility of large, multi-tenant public cloud offerings for their business and customers.
Cloud service providers have even made the choice easier, with ERP vendor NetSuite recently announcing a partnership with Amazon's S3 cloud storage form.
However, Frost & Sullivan industry director Andrew Milroy suggested that public cloud is the only type of cloud.
"A lot of companies like IBM and CFC and so forth that talk about private clouds are really just re-badging existing offerings," he told Computerworld Australia. "Effectively you've just virtualised that environment and made it more service-oriented.
"Private cloud is, in a way, muddying the water."
Though traditional private cloud and hosted data service providers like IBM, Oracle and CFC would conjecture with the argument that private clouds were more secure, Milroy said it wasn't "rocket science" to address those issues in a public environment.
"My view is that security is a red herring; it's just used by certain vendors to make people feel that they shouldn't go for the public cloud. They should stick with basically what they already have."
Milroy said that public clouds were an inevitability for most businesses.
"I think we're going to see a massive move towards public [cloud]," he said. "And I think we'll see our traditional guys look at how they can host applications for people who want to offer public cloud services.
"You'll need a very good justification not to go public. It'll start seeming inappropriate to have those resources delivered on-site unless you have a very, very good reason for it. Because it won't be cost effective; it'll be an expensive luxury really."
In the short term, companies are likely to continue struggling with the geographic obstacles that keep them from moving to the cloud - bandwidth, latency and data transfer costs among them. However, new offerings from corporations like Amazon, Microsoft, Salesforce.com with off-shore data centres are likely to challenge IT managers in the near-future, as they consider the compliance implications, as well as the benefits of deploying applications and data to data centres in the US, Europe and Asia.