I enabled jaunty-proposed on a new jaunty box and upgraded kvm:
$ sudo apt-get install kvm
Reading package lists... Done
Building dependency tree
Reading state information... Done
ubuntu-vm-builder hal vde2 samba kvm-source kvm-pxe
The following packages will be upgraded:
1 upgraded, 0 newly installed, 0 to remove and 8 not upgraded.
Need to get 0B/1143kB of archives.
After this operation, 4096B disk space will be freed.
(Reading database ... 23790 files and directories currently installed.)
Preparing to replace kvm 1:84+dfsg-0ubuntu11 (using .../kvm_1%3a84+dfsg-0ubuntu12.3_amd64.deb) ...
Unpacking replacement kvm ...
Processing triggers for man-db ...
Setting up kvm (1:84+dfsg-0ubuntu12.3) ...
* Loading kvm module kvm_intel
The install, as you can see, went without a hitch.
Will report how the VMs handle when I have more data.