GnuPG in the enterprise

[Tony Shadwick]

Are there any good documents out there on managing GnuPG in the 
enterprise?

There are basic issues I need to be able to address, such as a situation 
when an employee leaves a company.  The admin needs to have the rights to 
revoke that user's public key, and be able decrypt any old messages to 
that user, and be able to decrypt messages sent to that user that are now 
being redirected to someone else for handling.

Are there established mechanisms for handling centralized key management 
in a company to where the Administrator has access to everything required?