This is (as Laszlo says) critically important for free software virtual machines that want to boot a UEFI BIOS, like ARM architecture ones. Previously even if y

This is (as Laszlo says) critically important for free software virtual machines that want to boot a UEFI BIOS, like ARM architecture ones. Previously even if your VM was free software (like QEMU/KVM), you couldn't ship the BIOS blob with a distro, except in a non-free subsection somewhere. Now the whole VM stack will be completely free software, and it will be straightforward to make it all just work out of the box. (The previous license for the FAT driver was "2-clause BSD but with an extra term forbidding use of the code outside a UEFI implementation". That's obviously not an issue for manufacturers putting UEFI BIOSes into real hardware, but it was a real awkward point for open source VMs, and it's great to see it's been resolved.)