tailored message on gdm greeter screen

[Gene C.]

I would like to put a tailored message on the gdm graphical greeter screen to 
indicate just which version of the system I am running -- I have multiple 
version installed on the same hardware and it is sometimes not clear which is 
running/has been booted.

I tried using the Systems Settings/Login Screen tool for gdm setting but 
changing messages there seems to have no effect.

Any ideas/tips?
-- 
Gene