IBM's goal with this product is to help customers build "private clouds," since some companies hesitate to host data and applications on public clouds, often due to concerns about security and reliability. The idea of a private cloud is to set up--on a company's own servers--the same sorts of efficiencies used by cloud providers, without having to entrust sensitive data to an outside organization.

"For most well-established, large enterprises, there is in general some distrust with public cloud services," says IBM's mainframe cloud initiative leader, Andrea Greggo. "This is driving the focus on wanting to contain these environments behind [a] firewall but still benefit from the value of cloud."

Customers can use IBM's new servers for the data processing typically expected of mainframes, but Greggo says the servers also let customers take advantage of products such as eyeOS.

But Frank Gillett, a principal analyst at Forrester Research, calls the term "private cloud" an oxymoron. He compares what IBM offers to virtualization services already offered by companies such as VMWare.

Gillett acknowledges that eyeOS is different from other virtual desktop systems because it allows users to access the desktop through a Web browser instead of a special application. Nonetheless, he remains skeptical because eyeOS is not based on a popular operating system such as Microsoft Windows. He believes many businesses will stick with virtualization services that let them use familiar software. Though some companies have tried to build Web-based operating systems, he says, "None of these startups have made it into the mainstream conversations."