Russell Coker writes:
I had also hoped that it would be really reliable and work with the latest kernels (unlike Xen) but it is giving me problems with 2.6.32 on Opteron.

This is a regression caused by a recent security fix (CVE-2010-0298, "KVM: x86 emulator: fix memory access during x86 emulation"). It appears to affect only recent Linux kernels running as guests on AMD systems, and it will probably be fixed soon.