Windows Service Accounts and Password Expiration

  Our security policies and standards have always required passwords to expire, 
requiring account owners to change the passwords on a specific periodic basis.  
We also have standards for when generic or trusted accounts are acceptable.  
For instance, we deem the use of generic accounts acceptable in purely machine 
- to - machine batch processes.  Still we require certain criteria, including 
password expiration.
  In the Windows server world there are generic accounts called "Service" 
accounts.  "A rose by any other name ......."  Until recently, so-called 
"service" accounts have slipped by this requirement.  But system admin folks 
have become more security aware (thank you very much) and some are starting to 
ask the question.  Should Windows "service" accounts be required to have 
password expiration?  I'm getting good arguments from both sides of the issue.  
Application availability VS adherance to standards, industry best practices, 
etc.  Keep in mind that we are in a patient care environment.  Any thoughts 
from the list?

- Jack