Note: this is just my opinion. The OSI board may have a different opinion if it speaks as a body.
Microsoft is spreading FUD (fear, uncertainty and doubt) with their latest anti-Linux patent campaign. If they had an actual, solid case of patent infringement, they would go to a judge, get an injunction against the distribution of Linux, and sell patent licenses for FreeBSD. The fact that they don't, but are willing to sell patent licenses for an unnamed set of infringed patents, says that they have no legal case.
Their claims of infringement are just claims. Unless and until they name the patents, nobody can tell if their claims are valid. Maybe they are? Maybe they aren't? Nobody but them can say, and they have a huge incentive not to say.
Microsoft's Horacio Gutierrez has been quoted as saying, "This is not a case of some accidental, unknowing infringement." In fact, yes, it is -- and until Microsoft names the patents, it will continue to be. Open Source developers want their intellectual property to be respected, and are willing to respect other people's property. If you look at real property law, you can see emblazoned all over it the principle that you must be effectively INFORMED of your trespass. The property must be posted, or if it not posted, you must be told verbally or in writing "you are trespassing". Without that specific notice, there is no trespass. Without Microsoft identifying specific patents, there is no infringement.
The real patent, one which wouldn't give Microsoft pause, is a patent on something which is basic to the industry, and which cannot be challenged as obvious or prior art. It can't be worked around (usually) and is very solid. If such a patent existed, Microsoft would do something like take a copy of FreeBSD (which doesn't use the GPL), and sell it with a license for this magical patent. That they don't do the obvious, makes it obvious that they can't, so they won't.
The only thing we have to fear is FUD itself.