In a surprise and historical move Microsoft has released its entire patent portfolio to Open Innovation Network (OIN) by joining the organization. Microsoft has released all 60,000 patents to OIN.

“We bring a valuable and deep portfolio of over 60,000 issued patents to OIN for the benefit of Linux and other open source technologies,” said Erich Andersen Corporate Vice President, Deputy General Counsel.

These patents also include those 235 patents that Microsoft once claimed were infringed upon by the Linux kernel. Linus Torvalds had dismissed those claims stating, “Microsoft just made up the number.”

It’s a major u-turn for Microsoft, which has a history of exploiting patents as a weapon against Linux players. This move brings an end to the long hostility between Linux and Microsoft.

There are more than 2,650 members, including numerous Fortune 500 enterprises, that make OIN the largest patent non-aggression community.

OIN has created a massive pool of patents affecting Linux and open source projects. The organization offers these patents on a royalty-free basis to member organizations. Companies not yet member of OIN can also tap into its pool of patents if they promise not to assert its patents against the Linux system.

Back in 2005, OIN was created by a group of companies with vested interests in open source. The goal was to fend off any patent attacks on open source companies. Founding members included IBM, NEC, SUSE/Novell, Philips, Red Hat, and Sony.

Microsoft has around 90,000 patents, but over 30,000 as still pending with the US Patent Office. Once those patents are approved, they will also become part of OIN pool.