OpenMosix development stopped a few months back, they never got a stable version/complete version released for the 2.6 kernel, it is just for 2.4. The availability of low-cost multicore systems and the inherent inefficiency in a cluster network (when compared to a multi core/CPU machine) made the project irrelevant for the most part.
A group has been working on a new project called LinuxPMI
which is based on the OpenMosix code, but I have no idea how well it works. They are targeting 2.6 at least, so it is a start.