Software: http://www.netfort.gr.jp/~dancer/software/dsh.html.en

Articles:

http://www.unixlore.net/articles/running-remote-commands-multiple-servers-ssh-dsh.html

http://www.ibmsystemsmag.com/aix/tipstechniques/systemsmanagement/DSH-Simplifies-the-Task-of-Managing-Multiple-Syste/