I'm not sure how anyone would get around 6,256,642, which is "Method and system for file system management using a flash-erasable, programmable, read-only memory", which honestly just sounds like the idea of a filesystem trivially applied to flash. It may be possible that some other filesystem would not match the description closely enough to be enforceable.
That said, two of the other patents are regarding long filename support in fat32. If the outcome of this is that fat32 is put to rest as the default embedded filesystem, I personally could not be happier about it.
It wouldn't surprise me if Microsoft's legal team was not trying to pull crap with Linux, the kernel, and the GPL here. I suspect that they're really going after the Navigation System patents and there's probably a legal reason why they have to prosecute as much of their portfolio as applies. IIRC this prevents the otherwise unprosecuted patents from becoming unenforceable at a later time because they were neglected or not tended.
IANAL, but I think that there is a bit of an exception in the legal doctrine of promissory estoppel (http://en.wikipedia.org/wiki/Estoppel#Promissory_estoppel), which says that one cannot withdraw a promise to another party that they have come to rely upon. If that promise is implied by inaction, it is still sometimes seen as a promise.
That said, two of the other patents are regarding long filename support in fat32. If the outcome of this is that fat32 is put to rest as the default embedded filesystem, I personally could not be happier about it.
It wouldn't surprise me if Microsoft's legal team was not trying to pull crap with Linux, the kernel, and the GPL here. I suspect that they're really going after the Navigation System patents and there's probably a legal reason why they have to prosecute as much of their portfolio as applies. IIRC this prevents the otherwise unprosecuted patents from becoming unenforceable at a later time because they were neglected or not tended.