As an obligatory note, Debian Lenny was released earlier today. Which means that sysadmins all over the world are starting to upgrade their servers.
There is an oddly little known tool that each and every sysadmin should install on at least one server they maintain, called apt-listchanges. It lists changes made to packages since the currently installed version. Sure that information will be overwhelming on major upgrades, but what is useful even on major upgrades is the capability to parse News files in the same way.
News files contain important information about the package in question. For example a maintainer could list known upgrade problems there, like is done in the lighttpd package. Or list changes in package specific default behaviour, like is done in Vim package.
Sure, you will notice these in time, but it's nice to get a heads up before a problem bites you.