For what it's worth, here's my fiddling with -s and modules. Consider the following toy module (With horrible style. Don't write real code like this, kids ;):

1: package MyMod;
2: #$value = "Ding!";
3: sub spit {
4:   return $value;
5: }
6: 1;
[download]

And the following little script:

1: use MyMod;
2: print MyMod::spit(), "\n";
[download]

With the following command line, this will print "Hey Monks!"

c:/monks/temp $perl -s ss.pl -MyMod::value="Hey Monks!"
Hey Monks!
[download]

If, on the other hand, I uncomment line 2 in MyMod.pm, setting the default value of the variable to "Ding", the same command line will return the value set in the module.

c:/monks/temp $perl -s ss.pl -MyMod::value="Hey Monks!"
Ding!
[download]

To my eyes, this allows -s to set uninitialised module variables from the command line, but it will not override variables already defined. I don't really see how this can come in handy though. Perhaps some funky obfuscation?

Oh well. Curiosity strikes again :)