If you like to use your arrow keys in an interactive Python on OS X, you definately need readline. But what do you do, when installing py-readline via DarwinPorts doesn’t work??
Today i found this:

I had the same problem. If you download the patch files yourself from ftp://ftp.cwru.edu/pub/bash/readline-5.1-patches (readline51-00[1-4]) and put them in /opt/local/var/db/dports/distfiles/readline, then port install readline will work.

DarwinPorts in Ruby on Rails

this might be useful for other packages which can’t be fetched with the ‘port install <package>’ command