list requested ports:
port echo requested | cut -d ' ' -f 1 | uniq
list installed ports:
port -qv installed
When ports are updated, the old port is only deactivated, not uninstalled:
... autoconf @2.69_2 autoconf @2.69_3 autoconf @2.69_5 ...
You can see a list of all installed ports:
port echo installed
After you run MacPorts for a while, you will see a lot of duplicate ports. You can clean these:
sudo port uninstall inactive