Shuttleworth states plainly, "We have declined to discuss any agreement with Microsoft under the threat of unspecified patent infringements." He believes such threats "carry no weight whatsoever" and have no legal merit. Still, Shuttleworth says he appreciates Microsoft's claimed commitment to Linux-Windows interoperability and suggests Canonical and Microsoft could do "wonderful things" together, albeit not under the threat of patent infringement lawsuits.
Shuttleworth's position is especially interesting considering the popularity of Ubuntu Linux and Dell's decision to adopt the operating system in some of its consumer PCs. Even with the GPL v3.0 license apparently unlikely to take hold in the Linux kernel, Microsoft's efforts could suffer if more Linux vendors mirror Ubuntu's stance. (Thanks to Ars Technica for the tip.)