Also, AFAICT, it seems the Kernel is now based in Ingo Molnar's RT patchset.
(Linux version 2.6.26-rt-lab126 (build@ubuntu-jaunty-build-01) (gcc version 4.1.2) #5 PREEMPT RT Sat Jul 31 01:09:00 PDT 2010)
(
http://www.kernel.org/pub/linux/kernel/projects/rt/)