Today we announced that the Virtual Hard Disk (VHD) format is now freely available for use under our Open Specification Promise (OSP), and can be used in any development model without license for free, and forever. This decision was the result of many conversations over the last several months with our customers, partners and the open source community. By adding the VHD to the list of specs covered by the OSP, we hope to expand the virtualization market and foster interoperability among all virtualization solutions.

As part of Microsoft's ongoing commitment to interoperability, we will continue to evaluate our broad list of specifications and consider them for use within the OSP model. We welcome feedback on this subject, as discussion with the community is critical to our vision of interoperability.