The article starts with explaining that while Sun may have patents covering Java, and while IBM may have patents covering C compilers, Microsoft is the only large software company that "has declared itself the enemy of GNU/Linux and stated its intention to attack our community with patents". A sensible conclusion here is that Microsoft can certainly pose a threat to the GNU/Linux community.
So, does the Community Promise do anything to mitigate the threat from Microsoft? According to the Free Software Foundation, it does not. According to the FSF, there are several libraries included with Mono and used by applications like TomBoy that are not covered by the ECMA standards - and therefore, not covered by the Community Promise. They explicitly state that they are not referring to the Windows-specific parts like ASP.Net and Windows Forms. "Instead, we're talking about libraries under the System namespace that provide common functionality programmers expect in modern programming languages: binary object serialization, regular expressions, XPath and XSLT, and more," the FSF writes.
There is an additional problem with the Community Promise, the FSF explains. The Community Promise only covers claims on Microsoft patents that are necessary to implement the ECMA specifications. "Judging just by the size of its patent portfolio, it's likely that Microsoft holds patents which a complete standard implementation probably infringes even if it's not strictly necessary - maybe the patent covers a straightforward speed optimization, or some common way of performing some task," the FSF writes, "The Community Promise doesn't say anything about these patents, and so Microsoft can still use them to threaten standard implementations."
The FSF also details what Microsoft should do in order to quell any concerns the Free software community might have when it comes to Mono and C#: "If Microsoft genuinely wants to reassure free software users that it does not intend to sue them for using Mono, it should grant the public an irrevocable patent license for all of its patents that Mono actually exercises."
While I generally find the FSF over-the-top and out of touch with reality, I think they have raised some very serious concerns here, concerns Microsoft should address. It seems like Microsoft is more interested in keeping the patent situation a grey area, instead of actually removing all the fog around Mono.