"For years Microsoft has insisted that open-source vendors acknowledge its patent portfolio as a precursor to interoperability discussions. Today, Microsoft shed that charade and announced an interoperability alliance with Red Hat for virtualization. The nuts-and-bolts of the agreement are somewhat pedantic, providing for Red Hat to validate Windows Server guests to be supported on Red Hat Enterprise virtualization technologies, and other technical support details. But the real crux of the agreement is what isn't there: patents. Red Hat has long held that open standards and open APIs are the key to interoperability, even as Microsoft insisted patents play a critical role in working together, and got Novell to buy in. Today, Red Hat's vision seems to have won out with an interoperability deal heavy on technical integration and light on lawyers."