This script is based on the quakenet.pl script I first found on http://www.oberkommando.org/~senneth/irssi/scripts/ — I only extracted the message formatting part, though.
Many IRC servers introduce reply codes which are not, or not fully supported by Irssi. Since I was an avid user of QuakeNet and Undernet IRC networks, which are both running the same software, I was dissatisfied with Irssi’s presentation of the /whois output.
In particular, this script formats the reply containing the user’s account name (this is used by network services), the user’s actual IP and hostname (the hostname shown in the user@hostname string may be replaced with a custom one on these networks), and whether the user is connected via SSL (this is an extension not present on QuakeNet or Undernet, though).
This script is not really important, but it was important to please my aesthetical senses.