To install Solaris 11 as a guest on KVM the following steps are needed.
I will use Ubuntu 12.10 (Quantal) with KVM (qemu-kvm package) and Virtal Machine Manager (virt-manager package). Ubuntu uses a 3.5 Linux kernel.
I will use the sol-11_1-text-x86.iso to install Solaris.
Create a new VM with:
OS Type: Solaris
You will have to click "Show all OS options" before Solaris is available in the list. The list doesn't contain Solaris 11 yet, that's why I chose OpenSolaris.
After installing you will need to install slim_install to get a graphical environment:
pfexec pkg install slim_install
pfexec svcadm enable gdm
pfexec init 5
Now you need to remove the Tablet device which is used to keep the pointer of the host and the guest in sync, otherwise your mouse won't work.
Now you should be able to power-on your machine and use GNOME.
Have fun with SMF, ZFS and all other Solaris features!