Gerd today posted patches to upstream QEMU which support SPICE graphics.
They have not been accepted / merged yet, but I'm optimistic that the
command line syntax will not change significantly.
http://lists.gnu.org/archive/html/qemu-devel/2010-04/msg00967.html
This patch series adds corresponding support in libvirt's QEMU driver.
Although this patch series adds support in the XML RNG for a password
expiry time, this functionality isn't wired up in this patch series
since I need more time to write fallback code for cases where QEMU
doesn't do expiry itself.
Daniel