Sun and OpenSolaris.org on Monday released the first publicly available version of the OpenSolaris operating system  since work on the project began in 2005. 

The operasting system, which is a single distribution that can be used for desktop, server and HPC deployments, is based on the Solaris kernel and uses Sun's ZFS as the default file system.

OpenSolaris.org officials said the release (available here) is targeted at developers and early adopters looking for a powerful free operating system and to learn more about ZFS, DTrace and other technologies. The OpenSolaris project was created by Sun in 2005.

The two made the announcement at the CommunityOne Developer Conference in San Francisco. Sun also said it would launch a supported version of OpenSolaris. 

Just like Red Hat and Novell do with their open source Linux operating system projects, Sun hopes to use the free version of the OpenSolaris software to spark innovation in its supported OpenSolaris platform.

The OpenSolaris operating system will butt heads with the Linux open source operating system, which has been steadily growing over the past few years and makes up about 4% of the overall spending in the server operating system market, according to a recent IDC study. That number is expected to hit 9% in the next three years.

But the report notes that Linux could face challenges from OpenSolaris if the operating system begins to find favor on x86 platforms.

With Monday's announcement, the watch is on for x86 platforms.

Monday's news comes three months after the resignation of high-profile OpenSolaris.org member Roy Fielding, co-founder of the Apache HTTP Server Project and a key contributor to the hypertext transfer protocol (HTTP).

Fielding's Valentine's Day resignation message showed no love loss for Sun.

"Sun didn't just make vague statements to me about OpenSolaris; they made promises about it being an open development project. That's the only way they could get someone like me to provide free labor for their benefit," he wrote in a community discussion forum posting.

"Sun agreed that ‘OpenSolaris' would be governed by the community and yet has refused, in every step along the way, to cede any real control over the software produced or the way it is produced, and continues to make private decisions every day that are later promoted as decisions for this thing we call OpenSolaris," Fielding wrote.