qemu-2.2.0 in rawhide, virt-preview disabled for F20
qemu-2.2.0 was released yesterday, check the release announcement and fine grained changelog. Packages are available in rawhide and fedora-virt-preview for Fedora 21.
But now that Fedora 21 is out, there won't be any new builds for F20 virt-preview. If you want to play with the latest and greatest virt bits, you'll need to update to F21.