I needed to move some of my VMs from local storage to my shared iSCSI LVM volume.  I figured it involved qemu-img so I went to the interwebs to find how others did it.  Well, whaddya know, this recipe was perfect: http://bigmyx.blogspot.com/2012/03/convert-kvm-qcow2-file-to-lvm-disk.html

Thanks bygmyx!