Apple will unveil its first dedicated rack-mounted server at its Cupertino headquarters today.

Few details have been revealed about the product ahead of its debut – but Apple CEO Steve Jobs gave a brief preview of the server during his keynote address last week at the Worldwide Developer Conference.

What is known: the hardware takes up 2U (3.5-inches) of vertical space and will run Mac OS X Server. A photograph of the product shown briefly at Apple’s conference suggested a black-&-silver design in keeping with the company’s penchant for stylish hardware.

Small and convenient Long anticipated by Mac enthusiasts, analysts this week said they expect the server to be an important addition to Apple’s product line for such tasks as file serving, print and email serving, and Web hosting.

“I would see this as being a predominately complementary product for the markets where Apple plays,” said Gordon Haff, a server analyst with research company Illuminata. “If you’re Apple, you don’t really want someone bringing a Windows server in if you’ve got the desktop environment sewn up.

“It will do pretty much all the functions that small servers are used for,” he added.

The size and shape of rack-mounted servers provides a convenient way of storing large numbers of them in a small space. Space issues can be particularly acute at schools – traditionally an Apple stronghold – some analysts said.

“The trend has been more and more toward rack-mount servers,” Haff said. “They are more and more common even in small and medium-sized businesses.”

Unix boost Apple’s switch to Mac OS X, a Unix-based operating system that supports multiple processors, has facilitated the move, analysts report.

In its early days, the company offered its own version of Unix, called A/UX, according to Haff. “They were never really successful with it,” he said. “They made a bit of a play in the low-end server space, but we’re talking about relatively ancient history here.”

Dan Kusnetzky, vice president of systems software research with IDC, said: “For a long time, Apple really didn’t have an operating system that allowed it to be able to sell a mid-range server. It wasn’t set up for that.”

Apple currently offers G4 server towers running Mac OS X Server.

With the introduction of Mac OS X, Apple buoyed its operating system with the help of Unix. OS X is based in part on BSD, an operating system with roots in early versions of Unix from Sun Microsystems and others, Kusnetzky said. “It has been a server operating environment for quite a number of years,” he noted.

Thanks to its ties to Unix, “Mac OS X has the potential of going anywhere Unix goes,” Kusnetzky said, citing examples such as small embedded-appliance servers, and mid-range and mainframe servers. “As a category, Unix covers the gamut, from the very, very small to the very, very large.

“I’m not saying that Mac OS X is ready for all these different configurations, but it certainly has the potential.”