I haven't made a sim package yet, but there is a whole new set of packages on
www.linuxcnc.org/experimental/Karmic/
I would appreciate if folks could test the kernel and the rt packages, because as you said, it would be good to pound these outas much as possible before the next release.
The kernel there is made from the latest karmic ubuntu kernel with rtai patch added a few configuration changes for realtime stuff. It is compiled for smp (dual processor/core) just like the stock ubuntu kernel, but it should work fine on single core as well. I've been running it on my main machine with the nvidia video drivers, and running all kinds of programs and server software without a hitch for a week or so now.
I had the black screen problem on one computer with the last kernel that was up there, and I think it had to do with the onboard video chipset. There are more bug fixes in this kernel so it may work better.