csshX is a tool to allow simultaneous control of multiple SSH sessions. csshX will attempt to create an SSH session to each remote host in separate Terminal.app windows. A master window will also be created. All keyboard input in the master will be sent to all the slave windows.
Advanced features include enabling and disabling individual terminals, window layout and size controls, wild-card host-names, subnet scanning.
For full details, please see the manual page.
This software currently works on Intel/PPC OS-X 10.5, 10.6 and 10.7 (32 and 64 bit). An older version is available for OS-X 10.4.