Hi,
attached you will find a improved and more robust version
of if2mac initscript and a example configuration file.
The script is tested only on 2 systems, my desktop (3 nics)
and my router (12 nics + wlan) and seems to work so far.
If there are any bold testers who want to give it a try
their feedback, hints, critics and improvements are
appreciated.

What works:
1) basic renaming of interfaces based on configuration file
     is stable.
2) Interfaces of type en*, et*, wl* unknown to the config
    file are added to the end of the list on the fly and renamed too
    as they would stay as ethXrenamed after the first pass.
    A warning is printed and the user is invited to add them
    to the config file. If you know a better solution please tell me.

What doesn't work:
1) I cannot get to log if2mac to /var/log/boot on one box
      but I'm sure it runs as I see the messages about the
      renamed interfaces in dmesg. Could be just a wrong
      configuration or something I changed and cannot recall.

What I removed from this version:
1) I attempted integration with udev/eudev by generating
    a 70-persistent-net.rules  file on the fly at boot
    so that if drivers are rmmod and insmod again 
    there is at least a minimal chance that they get the same
    name as before (udev can still fail at it if you add more than one
    interface at once).
    File creation part worked, but at the next reboot udev/eudev
    tried to use it and made a mess. Ideally it should be
    removed at shutdown/reboot but in case of a crash
    or blackout it would be still there at boot making trouble.   
     In the end I removed it as udev/eudev is not reliable
     in doing this renaming anyway if you have more than
     than a few interfaces.   

Ciao,
Tito