I just upgraded a package that put up a debconf dialog telling me
 that it's moving some files from an old location to a new one, and
 that it will automaticly update the system wide confile.  It also
 says that any user .config's will need to be hand updated.

 It occurs to me that a message like that one ought to have an
 attribute you can set on it saying "send this to a sysnews system",
 so that when users log in after an upgrade, they see a message about
 it.  The sysnews system could be an email list, a login news feature
 run from the shell login profile scripts, or a web site, I suppose.
 It should at least perhaps be a log file for root.