I did something similar to this, but with a shell script. I created a directory 'ssh' in my home dir, with a script ssh.sh, which I symlink to the short names of the servers I wish to attach to. I didn't care about shortname->longname expansion because tab completion was fast enough (for boxes that didn't end in one of the local domains anyhow).

#!/bin/bash
if [ "$1" == "" ]; then
   ssh $1@$0
else
   ssh $0
fi
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So, when I want to connect to myhost.org with the username 'radmat', I can just:

$ ~/ssh/myhost.org radmat
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When I can't remember usernames, I make an entry in ~/.ssh/config to remember it for me. Hostnames are expanded by tab completion, and this saves me a ton of time.

Perl equivalent, if you want:

#!/usr/bin/perl
if (!defined $ARGV[0] || $ARGV[0] eq '') { 
   exec('ssh',$0) 
}
else { 
   exec('ssh',"$ARGV[0]\@$0") 
}
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