Microsoft announced that it is releasing a collection of software drivers under the GPLv2 to better enable Linux to run as a first class citizen on their Hyper-V technology. Matt Aslett and Stephen O'Grady provide excellent commentary [as always] and I won't rehash their discussion here.
This is a significant move by Microsoft.
It isn't the first time Microsoft contributed code under the GPL. In the early part of the decade (~2000) the Interix team contributed a reasonable amount of code to the gcc compiler suite that was accepted. We assigned rights of ownership to a Microsoft asset to the FSF as needed. We published the sources as the license required. But that was a different time and a different climate and the last thing Microsoft wanted to do was admit they were contributing to a free software project outside their walls, or that they were shipping software covered by the GPL in a Microsoft product.
Neither is it the first time they've shared their own code. Rob Mensching has been running the Wix project since 2003. That's a project started on SourceForge using a non-Microsoft license (the IBM Common Public License) using a software tool base that is still in significant use inside Microsoft for delivering products.
But then things appeared to shut down from a code perspective. Much of the past five or six years has been Microsoft contributing anything but code. Money to Apache or Eclipse, providing a site where others can contribute code, ensuring third parties make arm's length contributions rather than Microsoft staff, and esoteric contributions such as requesting approval for licenses from the OSI. Their messaging remains guarded. The "position paper" released in March co-incident with the Open Source Business Conference had the same move-to-the-middle ambiguous messages and excuses that began in ~2002 with the Shared Source Initiative. [Misquoting a study to try to demonstrate open source software is still rough and only developer friendly doesn't win them points either.]
The current Linux contribution is significant. It's a significant quantity of code. It's an attempt at direct participation in a major mainstream open source software project to meet business objectives. It should be encouraged. It's an opportunity for the Linux community to embrace-and-extend Microsoft.
As Stephen O'Grady observes at the end of his commentary:
"Microsoft is, this week’s contribution notwithstanding, still holding open source at arms length, in contrast to an IBM who embraces it strategically in certain areas in service of a larger strategy.
But while it is not a conversion, it is important news, a welcome development, and a job well done for those involved. "