MOSS 2007: Enforce document storage business rules by using Document Policy.

o Create a custom document policy.
o Deploy a document policy by using a policy feature.
o Specify logic for a document policy by using a policy resource

• .  Create Policy Feature:  Code Snippet
• .  Create Policy Manifest:  Code Snippet
• .  Create Policy Configuration Page:  Code Snippet
• .  Register the Policy Feature in the Policy Catalog. 

Reference:    Ton Stegeman

Note:  Script may have not entirely workable.  Please recheck the steps.

o Expiration:  Manage document retention rules by using the expiration feature policy.
o Expiration:  Launch a workflow when a document expires.