Linuxworld has an article regarding Microsoft's recent public statements regarding possible IP infringement in Linux and FOSS, and there is a quote that is not as notable so much for its content as its source:

Some observers say the possibility of Ballmer asserting rights to patents that Linux may have potentially infringed upon is slim.

"At this point I think it is more of an intimidation tactic," says Laura DiDio, an analyst with the Yankee Group. "To tell you the truth, if I am Joe IT, I don't know if this is much of a deterrent to me. Quite frankly, you have to prove [patent infringement]."

I agree, but more and more, I don't think this is as much about an attack on Linux as I did initially. The FUD that Mr. Ballmer spewed was genuinely not part of the deal, and I believe this is why Novell had the reaction they did.

This deal is designed to undermine the EC Antitrust Ruling, allowing Microsoft to now argue that Novell (formerly a plaintiff against MS in antitrust litigation) sees the value and necessity in paying license fees and royalties to interoperate with Windows.

Microsoft was worried that the EC ruling establishes a precedent of compulsory licensing, which Microsoft contends would stifle innovation if they were required to do so. As analyst Matt Rosoff put it:

Analyst Rosoff maintained that Microsoft is concerned about the long-term precedent of having a governmental body force it to do something to its core product. From Microsoft's point of view, he explained, it "owns Windows and it doesn't make sense that a government body should dictate design points in it."

Microsoft also has intellectual property concerns about the EC decision, he added. "It doesn't want what it views as its intellectual property to go into a general public-type license, a GPL-type license, where it can be freely shared," he said.

Perhaps Novell also is wary of such a precedent, they do have a significant "IP Portfolio" of their own, as they have been noting themselves.