I suppose april fools is the reason we've gotten so far through this discussion that only scattered mentions of fabric or puppet/chef?
I've certainly done my share of ssh in a for loop, but if you're seriously considering this you almost certainly want to look into puppet/chef/cfengine/etc.
Now that <a href="http://devstructure.com>blueprint</a>; exists, it's radically simple to turn your current environment into chef/puppet deploy script. That said, distributed shell tools like this are still tremendously useful and should be part of any cluster stack.
I've certainly done my share of ssh in a for loop, but if you're seriously considering this you almost certainly want to look into puppet/chef/cfengine/etc.