Sun announced Tuesday that it is buying Innotek, maker of VirtualBox, virtualization software that may have more value for software developers than data-center administrators.

Steve Wilson, vice president of Sun's nascent xVM virtualization line, called the purchase a "huge deal" for xVM and "even Sun as a whole," on his official blog Tuesday. Terms of the deal to buy the German company, expected to close in Sun's fiscal third quarter, were not disclosed.

"VirtualBox is software designed to allow users to run multiple operating systems on top of whatever OS they currently have installed," he wrote. "Whether you choose Windows, Mac, Linux or Solaris as your default desktop of choice, VirtualBox will ride on top of it and allow you to 'host' any arbitrary collection of operating system instances. Software developers everywhere are starting to discover this way of operating, and these desktop virtualization solutions are quickly becoming part of the common developer toolkit."

"While there are other applications that provide this capability, VirtualBox is free, open source and supports a wide range of operating systems," Wilson added. The software has been downloaded more than 4 million times since it was released roughly one year ago, according to Sun.

VirtualBox may sound similar to Sun's own xVM Server, but the two products are targeted at different markets, Wilson said. xVM Server, announced in November, is a hypervisor that installs on top of the hardware. "It's a purpose-built software appliance with functionality to enable server consolidation and dynamic IT. ... This is data-center grade virtualization," he said.

In comparison, VirtualBox is "a software developer's dream," he said. "You can easily set up multiple virtual machines to develop and test your multitier or cross platform applications -- all on a single box. ... Where xVM Server is competitive with something like VMware ESX Server, VirtualBox is more like VMware Workstation/Fusion or Parallels Desktop."

The product will continue to be free, and for strategic reasons, according to Wilson. "The developers that build applications have a huge amount of influence on how they're deployed. We believe that developers using VirtualBox can help guide their friends in the data center towards xVM Server as the preferred deployment engine," he said.

Sun may also look to align VirtualBox with its other developer-oriented assets, such as NetBeans and Glassfish, he said.

"Having a virtual lab story -- assuming it works and developers and QA like it -- is good for a developer-friendly company like Sun," said Michael Coté, an analyst with Redmonk. "But I'm not familiar with VirtualBox, so I don't know if it in particular is good or bad."