Groklaw StoryWell the MS FAT patent has been overturned thanks to the public patent foundation
Fricken Sweet.
FAT is not that great of a filesystem, but it has become a de-facto standard for cross-platform removable media including (for example) floppy disks, zip disks, flash drives, MP3 players, and some digital cameras. While it's not great, it's also not too bad for these limited appications.
This means that MS won't be able to use it's patent to lock out interoperability with open source projects.