From a mailing list entry by William Davis, ::

    sudo rm -rf \
   /opt/local \
   /Applications/MacPorts \
   /Library/Tcl/macports1.0 \
   /Library/LaunchDaemons/org.macports.* \
   /Library/StartupItems/DarwinPortsStartup

Why? Well if like me you run into some strange OS X dynamic linking issues and want to reinstall all your ports, or if you want to try out fink and make sure you don’t end up hitting your old ports applications.