This is my RMS's first email reply to my original email.
It was followed by his second email.

This is part of the Free Software as Lego Article.

From: Richard Stallman 
To: Steve Parker 
Date: Sun, 4 Feb 2001 05:55:14 -0700 (MST)
Subject: Re: Clarification of GPL for user article

    Scenario 1) I modify GPL code - eg emacs - to suit my own needs, purely to 
    use the modified binary on my own system. I never intend, and never do, 
    distribute this in any form.
    My own interpretation of the GPL is that I am free to do this. 

That is correct.  In fact, this is one of the freedoms that are part
of the definition of Free Software (see
http://www.gnu.org/philosophy/free-sw.html).

    Scenario 2) I modify GPL code - eg a CGI library - to suit my own needs for 
    use on a publicly-available web server. This code is being run, by the 
    general public, on my web server. Should I, in this case, make the code 
    available? Under the GPL, must I?

The GPL does not require it.  But is not very good for the community
when people do this, so I am looking at a way that GPL 3 could
require publication in this case.