Some other distros for setting up a HPC cluster are mentioned here. They may be better choices for certain tasks.
• birgHPC is a distro for bioinformatics built using an adapted version of make_pelican. It adds MPICH2, as well as a suite of tools for bioinformatics including GROMACS.
• KestrelHPC is a system for setting up a cluster of netbooted clients, using a frontend machine that runs Debian or Ubuntu GNU/Linux. It is available as a .deb package. Now at its second version.
• ABC Gnu/Linux is a distro for setting up a HPC cluster that works in both live and installed modes. I have tried it in live mode on a virtual cluster, and it works nicely, in my experience. It has the ganglia monitor, which is nice for seeing the details of the operation of the cluser. The frontend node automatically begins to operate as a dhcp server, using eth0, so be careful not to interfere with existing networks if you boot it up.
• Cluster by Night is another live CD approach to setting up a cluster for MPI work. It works within an existing network, which is not the case with PelicanHPC. It seems to be a very nice solution when it is not possible to set up a private network.