There's really little point using MacPorts if you don't keep it up to date. After all, that's the whole point of a package management system, right? ^^
To keep MacPorts / DarwinPorts up to date, you just need to issue the selfupdate command. The problem I always saw with it though was it seemed as if it wasn't doing anything:
% sudo port -v selfupdate Downloaded MacPorts base version 1.442 The MacPorts installation is not outdated and so was not updated selfupdate done!
In fact what I later discovered was that it was doing something. The selfupdate command actually does two tasks: it issues the sync command to update your ports tree (vis a vis portsnap on FreeBSD) and then updates the framework itself. The not updated message is referring to is the framework, it still updated your ports.