The i386™ clients co-located with pointyhat netboot from it (connected nodes); all other clients (disconnected nodes) are either self-hosted or netboot from some other pxe host. In all cases they set themselves up at boot-time to prepare to build packages.
The cluster master rsyncs the interesting data (ports and src trees, bindist tarballs, scripts, etc.) to disconnected nodes during the node-setup phase. Then, the disconnected portbuild directory is nullfs-mounted for jail builds.
The portbuild user can ssh(1) to the client nodes to monitor them. Use sudo and check the portbuild.hostname.conf for the user and access details.
The scripts/allgohans script can be used to run a command on all of the ${arch} clients.