Free as in bombs

Free as in bombs
Linking to GPL libraries and freedom.
by David "Novalis" Turner

How are GPL libraries "free", I am sometimes asked, if we don't permit
proprietary software to link to them?

After all, Microsoft permits any software to link to their libraries (in
most cases; some recent Microsoft libraries don't permit linking to
copyleft software). I just got email suggesting that if someone linked
proprietary software to GPL software, FSF would "kick down [his] door and
turn over [his] desk." This isn't quite accurate; usually, I prefer to use
grenades to open stubborn doors.

More seriously, we don't choose to use the criminal provisions of
copyright law to have GPL violators hauled off to prison. We don't even
usually need to call our lawyers. But Microsoft has had people imprisoned
for violating their copyrights. My job would be a lot more fun if I were a
commando. I would cut my hair short and smoke cigarettes and carry only
small knives to ward off insinuations of compensation.

full: http://www.fsf.org/blogs/licensing/freeasinbombs