Key management

Does anyone have any suggestions on how to manage ssh keys in a large
environment? I am interested in configuring one or two management
servers where I can distribute files via rsync or perform remote command
execution. If I want to setup keys between the management server and a
large number of clients what is the easiest way to manage the keys.
Having to distribute keys to a large number of servers is labor
intensive and can be a management nightmare. I am aware of the security
implications of such a setup, is there a concept of a key management
server. This would be for openssh 4.1.
Thanks in advance,